feat: update registration conflict exception to specify existing user role in error message

src/auth/auth.controller.ts

@@ -77,7 +77,7 @@ export class AuthController {
     },
   })
   @ApiResponse({ status: 400, description: 'Validation error' })
-  @ApiResponse({ status: 409, description: 'Email already registered' })
+  @ApiResponse({ status: 409, description: 'Email address is already registered as an agent or user' })
   async register(@Body() dto: RegisterDto) {
     return this.authService.register(dto);
   }

src/auth/auth.service.ts

@@ -65,7 +65,10 @@ export class AuthService {
     });
 
     if (existingUser) {
-      throw new ConflictException('Email already registered');
+      const existingRoleLabel = existingUser.role === UserRole.AGENT ? 'agent' : 'user';
+      throw new ConflictException(
+        `Email address is already registered as an ${existingRoleLabel}. Kindly use a different email address for the new signup.`,
+      );
     }
 
     // Hash password