Studio should validate AssessmentItem answers on load and save

[kollivier]

Summary

Currently, the Studio UI expects for the data it receives to be valid and complete, but we are not validating answer data upon load or save.

In general, we need to be explicitly validating JSONFields in order to ensure that invalid data does not get saved to the database through a bug or other means.

This problem has led to issues #879 and #892, and could lead to more issues in the future until it is addressed.

Category

BUG

[kollivier]

Adding high priority due to possibility of data corruption.

[MisRob]

I am not sure why this has WIP label - I am currently not working on it, so I unassigned myself to make it clear if someone else would like to have a look (Or should I? Feel free to assign me again if I missed something).

This issue might require much broader discussion as it's related to the validation of all data, not only assessment items. We could validate everything before publishing, I guess, but when it comes to saving, we allow partial data to be saved to IndexedDB and then synced. We don't have much control over the sync part of the process. I am not sure about the complexity of this task. @rtibbles any thoughts?

[indirectlylit]

not a front-end task

[micahscopes]

This came up for me in #2498... see here and here.

There are a few issues here that I see:

1. we need to validate input in the UI to give users feedback during editing (I believe @MisRob has done quite a bit of work on this kind of thing for assessment items)
2. on a broader level, we still need a way to validate the application data in general (stuff that the user doesn't directly edit, but that's critical for the application to function properly)
3. sometimes it'd also be nice to have ways of fixing/migrating invalid data that's already been saved because of past bugs. See here for an example of the need for this.