CKeditor5 source code editor breaks with a <template> tag

[sahal-va]

📝 Provide detailed reproduction steps (if any)

When I have a <template> tag in ckeditor5, the editor breaks and 'Source' button doesn't work anymore.
It is reproducible in demo as well https://ckeditor.com/ckeditor-5/demo/html-support/
Enter following code in source editing mode and see if you can toggle source button anymore.
<template id"test"><h1>Hi</h1></template>

1. Enable source editing mode.
2. Enter html code with <template> tag.
3. Disable source editing mode and enable again.
4. You can see console error throwing.

✔️ Expected result

Source editing should work

❌ Actual result

Source editing breaks

[wimleers]

Drupal issue: https://www.drupal.org/project/drupal/issues/3385566.