[Solved] Given this ExceptionMappingInterceptor code snippet, what will be the output if the handler throws an error? intercept(context, next) { return next.handle().... | NestJS

NestJS - Interceptors

Given this ExceptionMappingInterceptor code snippet, what will be the output if the handler throws an error?

intercept(context, next) {
  return next.handle().pipe(
    catchError(err => {
      return throwError(() => new BadRequestException('Mapped error'));
    }),
  );
}

AThe original error is sent to the client

BNo error is sent; the request succeeds silently

CA BadRequestException with message 'Mapped error' is sent to the client

DA syntax error occurs and the app crashes

Step-by-Step Solution

Solution:

Step 1: Analyze the catchError block
When an error occurs, catchError catches it and returns a new BadRequestException with a custom message.
Step 2: Understand the effect on the client response
The client receives the new BadRequestException with message 'Mapped error' instead of the original error.
Final Answer:
A BadRequestException with message 'Mapped error' is sent to the client -> Option C
Quick Check:
Error replaced by BadRequestException [OK]

Quick Trick: catchError replaces original error with mapped exception [OK]

Common Mistakes:

Thinking original error passes through unchanged
Assuming no error is sent and request succeeds
Confusing syntax error with runtime error

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More NestJS Quizzes

Given this ExceptionMappingInterceptor code snippet, what will be the output if the handler throws an error?

Step 1: Analyze the catchError block

Step 2: Understand the effect on the client response

Final Answer:

Quick Check:

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