Add additional empty checks after field protection for update/insert.

[sfadschm]

Fixes #3896.

Description
This PR adds additional empty data checks to the Model update and insert methods.
These are needed because doProtectFields is currently called after the last empty dataset check, but can further remove elements from the data array.
See linked issue for details.

Will add tests later today.

Checklist:

• Securely signed commits
• Unit testing, with >80% coverage
• Conforms to style guide

[michalsn]

Yes, it makes sense to throw an exception here instead of a Builder class.

Waiting for tests, thanks.

[sfadschm]

Is there a way that I can do the database live test on my local setup? Like it seems like I only need to add credentials somewhere but I can't seem to find where.

[michalsn]

The simplest way would be to add/edit .env file and fill the database.tests.* part.

[sfadschm]

Well yeah, let's just pretend I never asked that....

[michalsn]

Thanks, @sfadschm!