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

**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

Start by reproducing the issue in Metadata: make a minor description edit and save without expanding General information, License, Person(s), or Institution(s). Trace the save flow from the save button and verify that the edit succeeds without the misleading contact-person email error.

Written by the indexing model from the issue text.