MAI: Error if form fields not mapped to corresponding field(s) in installed connector

Description

Steps to reproduce:

1. Set up the automation connector (with "Enable Auto-fill on forms" turned on).
2. Create an Episerver form that connects to the Contact table.
3. Set up field mapping.
4. Input sample data and submit.
5. See data sent to Hubspot.
6. Drag more form elements to the form, use settings by default, no field mapping setting.
7. Open the page that contains the form in view mode.

Expected: The page opens as normal.

Actual: The page shows an exception.

Note: The form works normally if "Enable Auto-fill on forms" is turned off.