In master only the 'choose a link' option on a form element does not work and instead triggers the 'You must supply a value here'/submits the form.

Steps to reproduce:

1. Go to a course and click on Add activity or resource.
2. Click on URL under resources and press add.
3. On the add new url form, locate the External URL field and click on the Choose a link... button.

Expected results:
The repository picker comes up

Actual results:
"You must supply a value here." or, if all the fields are already completed, the form gets submitted