create session form does not have proper form validation

[wolfskaempf]

No description provided.

[ostenbom]

@wolfskaempf What was the issue here?

[wolfskaempf]

If I remember correctly it was this: Not all form fields show proper error messages when their content is not according to what is expected. I think the validation itself is actually fine, it just doesn't tell the user what's wrong. This problem occurred especially often with the picture credit link, which is often too long.

[wolfskaempf]

This also happens with required toggle buttons. Now, all of them are optional, but in case we add a required one in the future (e.g. for accepting terms), we would need to make sure that the error shows up correctly to help users understand that they need to activate the toggle.