Logging the unhandledRejection's stacktrace to a database

[AmosSzust]

Hi
Despite my searching, I couldn't find a clear explanation about getting the stacktrace of an unhandledRejection.

When such exception occurred, Node throws a clear and concise stack trace that shows me the exact problematic line (2nd stacktrace line, userService.ts:91):

Error: Illegal arguments: string, undefined
at Object.bcrypt.compareSync (/home/appName/public_html/appNameServer/node_modules/bcryptjs/dist/bcrypt.js:265:19)
at /home/appName/public_html/src/services/userServices.ts:91:17
at Generator.next (<anonymous>)
at fulfilled (/home/appName/public_html/appNameServer/services/userServices.js:5:58)

I did the following:

.on('unhandledRejection', async (reason: any, promise) => {
        console.log(`${new Date().toISOString()}: Reason: ${reason}`);
        await firestoreClient.handleError(new AppError(true, `Reason: ${reason}`, 500));
        process.exit(1);
    })

AppError extends Error. The stack trace in the database contains the following which leads me to the unhandledRejection line and not to the original problematic line like in the above stacktrace: at /home/appName/public_html/src/appNameServer.ts:66:43
How can I have the nice and clear stacktrace with the relevant info so I can log it to my database?
Thanks

[bnoordhuis]

You'll want to log reason, not new AppError(...).

Keep in mind reason is usually an instance of Error but not always.

[AmosSzust]

When I logged reason, I only got the error string itself, not the whole object/stack.

Eventually I logged reason.stack which includes what I needed but it is pointing to the js file/line and not the ts file/line (like node is showing in its own logging when failing). Not perfect but enough for my needs.

If there is a way to get the stack of the ts file, it would have been better.

[bnoordhuis]

Maybe--enable-source-maps helps? https://nodejs.org/docs/latest-v18.x/api/cli.html#--enable-source-maps

[AmosSzust]

I'm using pm2 to run and it says here: https://pm2.keymetrics.io/docs/usage/source-map-support/ that it recognizes filename.js.map (I have this file for each js file) automatically and it throws the stack accordingly. This is exactly what I see in pm2 logs but internally, in unhandledRejection catcher, this is not the case.