Saving and edit is not possible without expanding the mandatory fields + misleading error message

[wuschLOR]

Describe the bug
You will be promoted a misleading error "Contact persons need a mail address" when trying to save an edit without at least once expanding General information, License, Person(s), Institution(s).

To Reproduce
Steps to reproduce the behavior:

1. Go to Metadata
2. Make a minor edit (e.g. change of description)
3. Click the save button
4. See error

Expected behavior
Saving works without expanding every subsection

Screenshots

Desktop (please complete the following information):

• OS: Kubuntu 20.04
• Browser Mozilla Firefox 86.0.1

Smartphone (please complete the following information):
not tested

Additional context
none