Discovered while testing MDLQA-19300

Steps to reproduce:

1. Log in as a teacher, go to a course and turn editing on.
2. Click on the 'Add an activity' link then click on the 'or browse for content on MoodleNet' link in the footer.
3. Enter an invalid profile e.g. qwerty and click 'Save and go'.
4. OBSERVE the never-ending loading

Will need to see if this is occurring on other versions of Moodle too. Only confirmed on the QA site using 4.5