Apparent race condition: Admin form for link plugin does not display url select2 box

[fsbraun]

Setup:

• Django CMS 4 (develop-4) latest (django-cms/django-cms@914558d)
• djangocms-url-config latest (a98d71a)
• ./manage.py runserver
• Create or edit a link plugin

Result: Only roughly 50% of the time an error is thrown

• The url field renders as TextInput.
• Console says query function not defined for Select2 s2id_id_site
• If in edit mode, a number appears in the text input field

Since this sometimes a server restart, a clearing of the browser cache helps, I fear it is some kind of race condition. Which prevents the two select2 fields to link.

A potential solution might be to catch the error and retry after a delay if the error is due to parts of the site / scripts not yet fully loaded.

[marksweb]

I get this issue all the time. It did stop for a bit while I was working on cms 4 integration [locally], but now in production, it's 100% of the time.

From "Add URL" admin I get Uncaught TypeError: $element.select2 is not a function