Distinguish error types

[tjconcept]

If a user posts content with a bad content-type or otherwise invalid request, I would like to provide a decent error message back.
I'm currently doing this by wrapping code using Formidable in a try-clause, which works, but also prevents any other lower level error in reaching the surface and getting properly logged.

How should I distinguish these operational errors from others?
Maybe Formidable could sub class Error and expose it's error class for use in something like e instanceof formidable.Error? That would be nice to someone using bluebird.

[gabeio]

As a side note: try-clauses are not good to wrap any production code in as node apparently runs slower (at least so I've heard)

[GrosSacASac]

Have a look #686

import formidable, {errors as formidableErrors} from 'formidable';


const form = formidable({ multiples: true });

form.parse(req, (err, fields, files) => {
    if (err) {
        // check for a very specific error
        if (err.code === formidableErrors.maxFieldsExceeded) {

        }
        console.error(err);
        // nice error message and httpCode
        res.writeHead(err.httpCode || 400, { 'Content-Type': 'text/plain' });
        res.end(String(err));
        return;
    }
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify({ fields, files }, null, 2));
});

[aderchox]

This answered my question as well, I know this has been mentioned in the docs too where it says:

May have error.httpCode and error.code attached.

But in my opinion it's not clear enough as this example by you (@GrosSacASac ), so maybe adding it to the documentation too is not a bad idea.
Thank you.

[GrosSacASac]

@aderchox added something in the readme e060e3f