PHP warnings from FileUrlWidget

I am not able to reproduce the issue with Drupal 10.3.x-dev (d4883273125fe) and File URL 2.x HEAD (commit https://git.drupalcode.org/project/file_url/-/commit/2598cbf53c8df4424b8...).

After typing in 'foo' in the remote file url input, I cannot simply switch to the "Upload file" radio and get a file upload input unless I click the "Remove" button. After I do that, I can upload a file without any issue, and the test entity is saved as expected.

Could you please extend FileUrlWidgetTest and reproduce the error?

Adding screenshot about what I see on my test environment.

#4 #5 This patch here prevents exactly that.
In the value callback, the URL now gets validated before is gets added as a field item.

PS: I re-tested on a clean 10.3.x core and file_url 2.x and found another issue, see 🐛 URL not sumbitted (missing context in JS behavior detach Active

Got it, #4 is when testing with a single-valued field (see point 1 below).
I was initially testing with multi-valued fields.

To clarify, the patch prevents invalid URLs to be added as a field item. This fixes 2 issues:
1. For single-valued fields, after submitting an invalid URL, and clicking back on "Upload file" radio, the file upload field is not visible anymore. This comes from ManagedFile::preRenderManagedFile interfering, as it sets the #access to FALSE if $element['#value']['fids'] is populated
2. For multi-valued fields, after submitting an invalid URL, an empty/broken field item gets added.