Image Editing does not handle failures gracefully

[westi]

The Image Editing tools in the admin do not handle failures gracefully.

For example if loading an image / rotating and image fails and returns a failure instead of an image you end up with a spinning wheel of failure.

To reproduce:

• Upload an image
• Choose to edit it to get to the crop, rotate, resize options.
• Edit 'stream_preview_image' in 'wp-admin/includes/image-edit.php' to always return false.
• Now try an rotation. Notice the spinner never stops spinning.

This is because the javascript doesn't register an 'error' handler on the img but only a load handler so when WP fails to return an image we don't handle the error gracefully.

[westi]

We need at least something like:

		img.error( function() {
			alert( 'Sorry, something went wrong.' );
			t.toggleEditor(postid, 0);
		} )

in refreshEditor

[azaozz]

In [18798]:

Add error message when loading the preview image in the image editor fails, fixes #18723