UnhandledPromiseRejectionWarning inside .map

[Piranit]

Bug Report

Current behavior

I have a simple route '/err'. It has logic where appear BadRequestException.
Since I have HttpExceptionFilter this BadRequestException should be caught by HttpExceptionFilter.
But when I use .map() function to iterate an array HttpExceptionFilter not catch this error and I have UnhandledPromiseRejectionWarning.

Not Working Code

@Get('err')
@UseFilters(new HttpExceptionFilter())
async err() {
    console.log(`err`);
    const numbers: number[] = [1];
    const res = numbers.map(async x => await this.test(x));
    return res;
}

async test(n: number) {
    return new Promise((resolve, reject) => {
        throw new BadRequestException('wrong number');
        resolve(n);
    });
}

Server Logs

(node:25899) UnhandledPromiseRejectionWarning: Error: [object Object]
(node:25899) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:25899) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Possible Solution

But when I iterate array with for loop and not use .map() HttpExceptionFilter successfully catches this error I didn't have UnhandledPromiseRejectionWarning.

Working Code

@Get('err')
@UseFilters(new HttpExceptionFilter())
async err() {
    console.log(`err`);
    const numbers: number[] = [1];
    const res = [];
    for (let i = 0; i < numbers.length; i++) {
        res.push(await this.test(numbers[i]));
    }
    return res;
}

async test(n: number) {
    return new Promise((resolve, reject) => {
        throw new BadRequestException('wrong number');
        resolve(n);
    });
}

Problem

So why there appear UnhandledPromiseRejectionWarning when I use .map() and not appear when I use for loop instead?

Environment

[System Information]
OS Version     : Linux 4.15
NodeJS Version : v10.16.3
NPM Version    : 6.9.0
[Nest Information]
platform-express version : 6.0.0
swagger version          : 3.1.0
typeorm version          : 6.1.3
common version           : 6.7.0
core version             : 6.7.0

[kamilmysliwiec]

You didn't await your array of Promises.
Please, use our Discord channel (support) for such questions. We are using GitHub to track bugs, feature requests, and potential improvements.

[Piranit]

@kamilmysliwiec did you mean ?
const res = await numbers.map(async x => await this.test(x));
Yes, I tried it but it does not help.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.