CKEditor 5 accumulates class properties when switch code language in Code Block

I cannot reproduce this as written.

I can reproduce it when I use "Full HTML" but not if I use "Basic HTML"

Do you have to save the node between changing the code language?

Yes, need to save the node.
(I forgot to mention it, I fixed the description.)

Thanks for reporting this, and following up in detail, @herp! 😊🙏

Also: WELCOME! 😄👋

Can you reproduce this at https://ckeditor.com/ckeditor-5/demo/feature-rich/? 🙏

We'll need to file an upstream bugreport. Did you check if this has already been reported at https://github.com/ckeditor/ckeditor5/issues?

It is reproducible here https://ckeditor.com/ckeditor-5/demo/html-support/

1. Open Source editing
2. Insert for example <pre><code class="language-c">int myNum = 15;
   

   in Source editing

3. Switch back to editor mode, select code block, change language to any other
4. Swith back to source. There are now 2 "language" classes in source

The problem occurs only with GHS (so in Drupal only when filter_html is disabled) when the view gets cast to model, it correctly detects language by class, but later instead of replacing it adds a new one.

I haven't found an existing issue about this at GitHub

I checked it, as did @ReINFaTe. There are 2 'language-*' properties in the class.

I also did not find any existing issue at GitHub.

Wonderful, thanks both of you! 🙏 Could you please create an upstream issue? 😊

This issue has been reported upstream at https://github.com/ckeditor/ckeditor5/issues/15453.

This issue blocks 🐛 When you change the code snippet lang from original to something else it breaks Closed: works as designed .