Error: Cannot read property 'id' of undefined when uppy.cancelAll() is called

First, I want to start by thanking you guys for working on such great file upload package.

To reproduce the issue try to upload multiple files using the AWS S3 provider

• Drag & drop multiple files into the file uploader or use the open file dialog.
• Abort/Cancel the upload using uppy.cancelAll()
• the file uploader will show an error alert Cannot read property 'id' of undefined

Please see the screenshots

The error alert

the thrown error

The block of code that caused it

maybe changing this condition https://github.com/transloadit/uppy/blob/1dd4d79aa79526cc52e516f7126e71d492b5f83c/packages/%40uppy/core/src/index.js#L855

to something like

if (!file || !this.getFile(file.id)) {
  this.log(`Not setting progress for a file that has been removed: ${file.id}`)
   return
}

may solve it?

[goto-bus-stop]

That check would work, but I think we should do it in the AwsS3 plugin itself, and not emit the preprocess-complete event if the file doesn’t exist anymore: https://github.com/transloadit/uppy/blob/733de659da17ee77afba9882633477fb7cd778dd/packages/%40uppy/aws-s3/src/index.js#L172-L175

(That if() statement in @uppy/core is a hack to try to paper over these bugs 😞 we should avoid emitting events with removed file objects as much as possible!)

@VivekSingh777 please do! lmk if you need any more pointers

[VivekSingh777]

Can I work on this issue?