fetch doesn't support blob images which are CORS.

[asimkt]

📝 Provide detailed reproduction steps (if any)

1. Upload & copy the uploaded image from https://udaychy.github.io/ImageBlobDemo/. (The idea is the image should be available as a blob)
2. Now paste the content in any CK Editor. (Products like Confluence page by default converts all images to its local blob after publishing)
3. Functions like isLocalImage and fetchLocalImage will run from packages/ckeditor5-image/src/imageupload/utils.js, which will in turn call fetch( imageSrc ).
4. The imageSrc in this case is like blob:https://udaychy.github.io/eea1fe2d-7dcf-48b9-a65c-31306a57ee70

✔️ Expected result

The image should be uploaded/gracefully fail.

❌ Actual result

Getting an alert from fetch API that, TypeError: Failed to fetch and in console we're getting detailed error that:

Fetch API cannot load blob:https://udaychy.github.io/eea1fe2d-7dcf-48b9-a65c-31306a57ee70. URL scheme must be "http" or "https" for CORS request.

So basically fetch API won't work for CORS blob.

📃 Other details

• Browser: Google Chrome Version 83.0.4103.61 (Official Build) (64-bit)
• OS: Mac Catalina 10.15.3
• CKEditor version: 23.0.0
• Installed CKEditor plugins: EasyImage

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[LukaszGudel]

PR #8707 is not fixing this issue. Additionally instead of alert with message TypeError: Failed to fetch it's now printing [object Event]. Also, when running paste-from-word manual test with changes from PR and following steps from this issue there is additional error in the console:

integration.html:1 
Not allowed to load local resource: blob:https://udaychy.github.io/978c8ea9-4dc7-4f43-aa5d-d6c483ff54b9 

[CKEditorBot]

There has been no activity on this issue for the past year. We've marked it as stale and will close it in 30 days. We understand it may still be relevant, so if you're interested in the solution, leave a comment or reaction under this issue.

[CKEditorBot]

We've closed your issue due to inactivity over the last year. We understand that the issue may still be relevant. If so, feel free to open a new one (and link this issue to it).