Etcher: Corvus emitting `[object Object]` error to Sentry

[jviotti]

[lurch]

Hmm, I guess this never got tracked down then?

[jviotti]

It got greatly reduced (like by 3/4), but there are still some occurrences that we should track down.

[Shou]

Looks like lib/child-writer uses a bit of .toString() which may be the cause.

[jviotti]

See the conversation in Flowdock. Its corvus applying JSON.stringify() on error objects, which results in empty objects, and also the utils.hideAbsolutePathsInObject function

[jviotti]

Looks like an easy fix though, for which we can even have some nice unit tests. Lets fix whatever utils.hideAbsolutePathsInObject is doing wrong and create and test a function that is able to stringify errors and plain objects.

[jviotti]

Check this SO answer: https://stackoverflow.com/a/18391400/1641422. We can use a replacer function for JSON.stringify():

function replaceErrors(key, value) {
    if (value instanceof Error) {
        var error = {};

        Object.getOwnPropertyNames(value).forEach(function (key) {
            error[key] = value[key];
        });

        return error;
    }

    return value;
}

var error = new Error('testing');
error.detail = 'foo bar';

console.log(JSON.stringify(error, replaceErrors));

[jviotti]

Looks like no lodash function works with Error objects. utils.hideAbsolutePathsInObject fails at a _.deepMapValues call, which doesn't really map anything, and thus returns an empty object.

[jviotti]

I guess an easy way to do it would be to create a function that converts an Error object to a plain object, but then utils.hideAbsolutePathsInObject should output an Error instance if that's what came in, so we would need to have a "reconstruct" function.

Probably easier to re-implement deepMapValues so that it can map through error objects correctly.

[Shou]

Wouldn't JSON.stringify still return {} if we gave it an Error object, so shouldn't we return an object from hideAbsolutePathsInObject? Or just report the Error directly and skip hideAbsolutePathsInObject?

[lurch]

Or just report the Error directly and skip hideAbsolutePathsInObject?

Is it possible that some of the Error's details (description) might contain the absolute paths that we're trying to hide? ;-)

[Shou]

Ah, so maybe the idea is to use the same function for both, but only pure objects get turned into a string with JSON.stringify before sent to the console.

[jviotti]

@Shou This problematic logic only applies when logging the error in DevTools, independently on the error being sent to Sentry. We stringify them since its very hard to view objects on DevTools otherwise. Making hideAbsolutePathsInObject work on Error objects and return a plain object should do the trick.

[Shou]

I've made https://github.com/resin-io-modules/resin-corvus/pull/22 now so let me know what you think.

[jviotti]

I can't tell for sure, given this issue has been particularly difficult to track, but as far as my experiments went (that involved sending actual errors to Sentry and check them out in the dashboard), this issue seems fixed by https://github.com/resin-io/etcher/pull/1604

[jviotti]

This issue was probably closed by https://github.com/resin-io/etcher/pull/1604. Let's keep an eye on the analytics and re-open if it happens again.

[lurch]

@jorgemanrubia I'm confused - Etcher isn't an ember app, so why have you posted a comment on an Etcher issue? Could you add more details?

[jorgemanrubia]

Ugh sorry about that @lurch, I meant to post this in the sentry issue tracker. I'll just delete my comment