RCC Error handling

[AndyRae]

We need to improve the general error handling, and user interaction with forms.

For example this is bad:

• Discover all the errors that we can provoke from forms
• Improve the error handling, with sensible messages.
• Or at least, catch them to stop useless message

For example, passing from the Next.js server actions to client actions, this should really be handled more like a traditional API. With error handling included.

If there is a significant amount of work here, then this issue is about discovering where it needs fixing, and the action is to list where we need to fix them.
So we can turn those into issues and refine-able work.

List of Errors to fix:

• Adding a new study ?