fix: handle null file types in image check

[ckotzbauer]

Suggested merge commit message (convention)

fix: handle null file types in image check

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Additional information

This PR fixes JS errors if files with null filetypes or null-files are processed by the "isImageType" function. I cannot reproduce such cases locally, but our customers can do this with D&D in the newest Chrome...

[coveralls]

Coverage remained the same at 100.0% when pulling 18b39cf on SamhammerAG:master into 25be8e0 on ckeditor:master.

[Reinmar]

I feel unsafe about this change being made in a util. It may hide some bigger issues if this util will be used in more places. I'd still not be ideal, but I'd move this code directly to the place where isImageType() is used. Most likely you mean this place:

ckeditor5-image/src/imageupload/imageuploadediting.js

Line 58 in 25be8e0

const images = Array.from( data.dataTransfer.files ).filter( isImageType );

Also, this seems to be a workaround for some Chrome bug, so that's why it'd be better to keep this change more locally.

[Reinmar]

BTW, any chance that you could find out more about how and when this issue occurs? It's a bit odd one :|

[ckotzbauer]

Yes, I mean this place with the datatransfer.
We currently try to find out more about this issue from our users. Hopefully we get some useful infos.

[Reinmar]

Do you think you could update the PR this week? We're finishing an iteration now and we would include it in the release.

[ckotzbauer]

@Reinmar Done, I moved the null check to the dnd-logic.

[Reinmar]

Thanks! It looks great.