How to avoid "TaskInstance XXX was canceled..." errors?


#1

Hey, I’m using ember-concurrency and I’m getting this error: TaskInstance XXX was canceled because it belongs to a XYZ Task that was .perform()ed again".

I’ve noticed that’s because I’ve used an ember concurrency task as a promise (task.then(...)) but I didn’t have a catch handler defined. Once I’ve added it (which wasn’t that obvious to me, I think this could be a good thing to add to the docs) the cancellation error was handled, but I’ve noticed that the error object in the catch handler I’m getting is just a string (same as shown in the console).

So now my last issue is, how do I distinguish between cancellation errors, and possible other errors in the catch handler? Imo it’d be great if I could import { cancellationError } from 'ember-concurrency' and use that to ignore the cancellation error and throw if some other issue occured.

edit: derp… ok I have now noticed that it’s not a string, and you can actually call e.name which gets you TaskCancellation, I’ll leave this up, maybe it’ll help someone in the future :sweat_smile:

edit2: Aaaand there’s an taskInstance on the error object which has a isCanceled CP, rubber duck driven development ftw :slight_smile:


#2

You might also want to check out using didCancel, which will let you check whether an error was a task cancellation and handle it differently. Depending on what you’re doing it might be a cleaner approach as well.