diff --git a/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache b/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
index 1c52f7f245b..95ca812b359 100644
--- a/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-angular/api.service.mustache
@@ -71,8 +71,9 @@ export class {{classname}} {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts
index 200ccbbf42e..9f012efcdac 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts
+++ b/samples/client/others/typescript-angular/builds/composed-schemas-tagged-unions/api/pet.service.ts
@@ -42,8 +42,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts b/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts
index 200ccbbf42e..9f012efcdac 100644
--- a/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts
+++ b/samples/client/others/typescript-angular/builds/composed-schemas/api/pet.service.ts
@@ -42,8 +42,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts
index d3616f85e38..8ef8b356076 100644
--- a/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-oneOf/builds/default/api/default.service.ts
@@ -42,8 +42,9 @@ export class DefaultService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts
index 1ae22faa555..1c9e3dfdeb4 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts
index 6cbca642375..bdfd5912cd0 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts
index a907ae063df..37db4c39a58 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-any/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts
index 8087e194df5..37e99580d9d 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts
index b9b57010552..bd0209428e5 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts
index 8fb4cf1140a..80cde7e0ec8 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts
index 8087e194df5..37e99580d9d 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts
index b9b57010552..bd0209428e5 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts
index 8fb4cf1140a..80cde7e0ec8 100644
--- a/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v12-provided-in-root/builds/with-npm/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts
index d3616f85e38..8ef8b356076 100644
--- a/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-oneOf/builds/default/api/default.service.ts
@@ -42,8 +42,9 @@ export class DefaultService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts
index 1ae22faa555..1c9e3dfdeb4 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts
index 6cbca642375..bdfd5912cd0 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts
index a907ae063df..37db4c39a58 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-any/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts
index 23e50e004ec..ffb70253eaf 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts
index 4ed6aad2797..c81fb3d27b9 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts
index 55744455ab6..f0251c55d36 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts
index 23e50e004ec..ffb70253eaf 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts
index 4ed6aad2797..c81fb3d27b9 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts
index 55744455ab6..f0251c55d36 100644
--- a/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v13-provided-in-root/builds/with-npm/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts
index 23e50e004ec..ffb70253eaf 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts
index 4ed6aad2797..c81fb3d27b9 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts
index 55744455ab6..f0251c55d36 100644
--- a/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-provided-in-root/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts
index bb24ea5bcca..6fd8ec5eed9 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts
index f2cd4b844fc..5eaf447f54b 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts
index fcd474cf958..7aa74420016 100644
--- a/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v14-query-param-object-format/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts
index 23e50e004ec..ffb70253eaf 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts
index 4ed6aad2797..c81fb3d27b9 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts
index 55744455ab6..f0251c55d36 100644
--- a/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v15-provided-in-root/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts
index 23e50e004ec..ffb70253eaf 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts
index 4ed6aad2797..c81fb3d27b9 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts
index 55744455ab6..f0251c55d36 100644
--- a/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v16-provided-in-root/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts
index bd9b9427f05..f4659b9300a 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/pet.service.ts
@@ -44,8 +44,9 @@ export class PetService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts
index a7cf0a83713..043bb8efa12 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/store.service.ts
@@ -42,8 +42,9 @@ export class StoreService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {
diff --git a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts
index 33ea990881e..2f3945435db 100644
--- a/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts
+++ b/samples/client/petstore/typescript-angular-v17-provided-in-root/builds/default/api/user.service.ts
@@ -42,8 +42,9 @@ export class UserService {
             this.configuration = configuration;
         }
         if (typeof this.configuration.basePath !== 'string') {
-            if (Array.isArray(basePath) && basePath.length > 0) {
-                basePath = basePath[0];
+            const firstBasePath = Array.isArray(basePath) ? basePath[0] : undefined;
+            if (firstBasePath != undefined) {
+                basePath = firstBasePath;
             }
 
             if (typeof basePath !== 'string') {