[Solved] What is wrong with this interceptor implementation? import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common'; import { Observable } from 'rxjs';... | NestJS

NestJS - Interceptors

What is wrong with this interceptor implementation?

import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common';
import { Observable } from 'rxjs';

@Injectable()
export class ErrorInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable {
    try {
      return next.handle();
    } catch (error) {
      console.error('Error caught:', error);
      throw error;
    }
  }
}

AThe interceptor should not throw errors

BThe intercept method must return void, not Observable

CMissing call to next.handle() inside try block

DThe try-catch block won't catch async errors from next.handle()

Step-by-Step Solution

Solution:

Step 1: Understand async error handling in interceptors
next.handle() returns an Observable, so errors happen asynchronously and are not caught by try-catch.
Step 2: Identify the problem with the try-catch
The try-catch only catches synchronous errors, so async errors must be handled with RxJS operators like catchError.
Final Answer:
The try-catch block won't catch async errors from next.handle() -> Option D
Quick Check:
Async errors need RxJS catchError, not try-catch [OK]

Quick Trick: Use RxJS catchError for async errors, not try-catch [OK]

Common Mistakes:

Using try-catch for async Observable errors
Assuming intercept returns void
Not handling errors inside pipe

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More NestJS Quizzes

What is wrong with this interceptor implementation?

Step 1: Understand async error handling in interceptors

Step 2: Identify the problem with the try-catch

Final Answer:

Quick Check:

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