Warning: a promise was rejected with a non-error: [object Object]

[chevin99]

I keep seeing this warning

Warning: a promise was rejected with a non-error: [object Object]

in the console when I make a request like below that results in an error (like a 500 status for example). The request works fine and I can catch the error no problem, but I'd like to get that warning to go away in the console. Any idea how?

let request = require('superagent-bluebird-promise')

request.post(url, data)
  .promise()
  .then((res) => {
    console.log(res);
  })
  .catch((e) => {
    console.log(e);
  })

[chevin99]

According to this comment on bluebird issue 990, it seems that the warning happens when the error doesn't have all of the following: .name, .message, .stack.

When I change this in the source

if (Object.defineProperty) {
    Object.defineProperty(this, 'stack', {
      get: function() {
        if (this.originalError) {
          return stack + '\nCaused by:  ' + this.originalError.stack;
        }

        return stack;
      }
    });
  }

to this

this.stack = this.originalError
    ? stack + '\nCaused by:  ' + this.originalError.stack
    : stack;

the warning goes away. It seems that the warning happens because bluebird doesn't recognize the existence of .stack when defined using that Object.defineProperty method.

[neekey]

same here : (

[oponder]

Yeah I'm seeing a promise was rejected with a non-error in my console a lot too, and I'm one of those guys that likes to have a clean console as much as possible :)

Do you guys consider this something that should be fixed in Bluebird? or can we get a bit less fancy with the definition of the stack property on SuperagentPromiseError like @chevin99 suggested. I'd be happy to make a PR.

Here is the definition of SuperagentPromiseError: https://github.com/KyleAMathews/superagent-bluebird-promise/blob/master/index.js#L25

Anyone know what benefit the Object.defineProperty way gives us?

[johanneslumpe]

@oponder It's even worse that those warnings show up in production. @KyleAMathews can you chime in here?

[KyleAMathews]

I'm not using this lib in production right now so would be happy to make any of you interested collaborators so you can make the needed changes and do a new release.

[johanneslumpe]

@KyleAMathews sure, would love to do that over the weekend!

[chevin99]

@johanneslumpe, any progress? Thanks for the help on this.

[johanneslumpe]

@chevin99 I didn't get to this yet :/

[Gekkio]

Making the stack property settable and configurable are the minimal steps needed to make Bluebird detect SuperagentBluebirdError objects as errors while keeping the Object.defineProperty call.

I've got a fix here but didn't yet submit a pull request as I'm not 100% sure it's the right fix. The warning is gone, but some functionality might behave differently.

[evegreen]

@Gekkio , your fix works perfectly, can u make PR please ?