Extending error object in express, but Debug does only show the stack trace

Hello,

Small question of which I don’t know it’s a bug or expected behaviour:

In my express application I have the following app.use at the bottom:

app.use( (error, req, res, next) => {
    const status = error.statusCode || 500;
    const source = error.source || 'Unknown';
    const message = error.message;
    const info = error.info || '';
    console.log(error); // For logging on the server
    res.status(status).json({
        status: status,
        source: source,
        message: message,
        info: info
    })
});

This shows me the stack trace and the error object (with source and info properties).

When I change the console.log to debug, it only shows the stack trace and not the error object.

Why is that? And how can I show the error object with the debug command also?

[Qix-]

Aha, I thought this got fixed a while back. Apparently not. Thanks for the repro case, by the way 😃

The first argument is not util.format’d where it should be.

The standard .toString() on Error objects does not include extraneous information. console.log() is, more or less, just (...args) => stdout.write(util.format(...args)). That’s why it’s showing the extra information.

For now, use a format string:

debug('%O', error); // 'O' as in 'Open', not a zero.

This will get fixed in the future.

[RAnders00]

I get the same behaviour using the make-error-cause package:

process.env.DEBUG = '*'

const log = require('debug')('test');
const { BaseError } = require('make-error-cause');

const cause = new Error('This is the cause!');
const error = new BaseError('This is the error!', cause);

log("---------")
log(error);
log("---------")
log("%O", error);

2019-07-05T20:26:56.917Z test BaseError: This is the error!
    at ...

2019-07-05T20:26:56.918Z test BaseError: This is the error!
    at ...

The following exception was the direct cause of the above exception:

Error: This is the cause!
    at ...