Summary

This MR fixes the student csv validation bug whereby the UI loads forever with an incorrect csv file. A new error pane has been added to catch server errors on csv validation.

Checklist

All items on this checklist should be checked.

I have added a changelog entry.
I have added a test that catches the original bug behaviour.
I adhere to the style guide.

How to review

Input an incorrectly formatted csv file when adding groups and students to a course
Validation should fail with an error in the UI
Input a correctly formatted csv file when adding groups and students to a course
Validation should pass, hiding the error pane

Screenshots

Validation fails with a server error

Validation passes

Issues and tasks closed

Closes #63