Cannot preview form when an unsupported field is required

Issue Summary

When adding an unsupported field that is required in the Forms, you can no longer preview the form and it would appear as unavailable.

Steps to Reproduce

1. Go to the field configuration of a project and make an unsupported field Required (eg. Security Level)
2. Go to the Forms of said project and add the field to the form
3. Click on Preview

After following those steps you should see the following message:

Making the field Required is a needed step to replicate this because without it, you actually can't add an unsupported field to the form.

Expected Results

A preview of the form should load in a new tab and if the field is unsupported, it should be locked or indicate that the field is unsupported.

Actual Results

The preview is loaded in a new tab with a "Form is unavailable" message.

Workaround

Change the requirement of the unsupported field to Optional.