Catch errors creating mocks
Summary: Fixes T16379
Test Plan:
- Go to https://phorge.localhost/pholio/create
- Add an image
- Leave all other fields blank
- See the form with a validation error ("Mocks must have a name"), not an unhandled exception
Reviewers: O1 Blessed Committers, mainframe98
Reviewed By: O1 Blessed Committers, mainframe98
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T16379
Differential Revision: https://we.phorge.it/D26565