Ensure uniqueBundleId is unique in LoadJS

Here is a patch that adds a counter and uses that to make sure that uniqueBundleId is always unique.

This fixes our issue with Flag and should fix the other referenced issues above.

The Needs Review Queue Bot → tested this issue.

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The Needs Review Queue Bot → tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

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Here's a patch from the MR.

Note that this patch is for 11.x while the patch in #2 above will apply to 10.x.

Thanks for reporting, as a bug can we get a test case showing the issue

Despite applying patch #2 for Drupal 10, the problem persists when request the controller for a response via AJAX dialogs.
The first request executes correctly, and the response is accurate on the second attempt. However, the same error continues to occur:
An error occurred during the execution of the Ajax response: LoadJS

Code snippet:

<a
   href="{{ url('controller_route_name') }}"
   class="use-ajax"
   data-dialog-options="{{ dialog_options|json_encode() }}"
   data-dialog-type="modal"
   data-ajax-http-method="GET"
>

After updating to Drupal version 10.3.1 (I was before at version 10.2.4), the "An error occurred during the execution of the Ajax response: LoadJS" error is generated on my custom code after CTAs with ajax actions that should replace page content. Big pipe is not enabled. So it should be related with the way I perform the ajax calls (or the addition of the libraries) and the way drupal 10.3 processed them.

Applying patch #2 solves the issue.

I've stumbled over this when trying to open a configuration on /admin/config/development/configuration more than once.
Might make it easier to reproduce in core only for testing.

Patch #2 worked for me.

MR now has a test. Tried to do this in \Drupal\Tests\system\FunctionalJavascript\ModalRendererTest but couldn't get the error there, maybe/probably due to the lack of JS/CSS on that page?

So I decided to use a bit of \Drupal\Tests\config\Functional\ConfigImportUITest in a new FunctionalJavascriptTest.
Not great, not fast, but we need JS testing for this and this was the only place in core I could reproduce the error.

MR passes, test-only fails where it's expected to fail.

Looking at the documentation for loadjs, there is a isDefined() method that checks for existing bundle IDs, so I think the counter might be unnecessary altogether. I created a new MR 9184 based on the original MR, and added isDefined() checks. It passes all tests, including the new one from #13.

godotislate → changed the visibility of the branch 3463875-bigpipe-loadjs-errors to hidden.

Believe adding the isDefined check makes sense.

Trying for a descriptive of what is being fixed. I also left 2 comments in the MR about documentation that need attention.

Thanks @quietone, applied your suggestion and added a comment.

Believe additional feedback has been addressed.

Hoping eventually can help close resolved threads but can't help there either :(