Error handling when editing exercises about codeocean

[MrSerth]

Trace 3161abf0-fa8a-45eb-96da-af39b5848b24 might be related to this issue

[franzliedke]

Because I was asked about it: this is about editing exercises as a teacher, not a student's submission.

[rteusner]

We fixed this here: #238

[franzliedke]

It doesn't seem like #238 changes anything about the fact that validation errors will cause all entered data to be lost. So if I forget to add another required field, the data will still be gone.

[MrSerth]

The changes are not deployed so far, we’ll notify you as soon as we did so.

// cc: @rteusner

[MrSerth]

The changes are now deployed.