R1:870b01f2d070

Distinguish between "bad record format" and "bad record value" when validating Trigger rules

Summary:
Depends on D20416. Ref T13269. See D20329.

If you try to save an "Assign to" rule with no assignee, we currently replace the control with an "InvalidRule" control that isn't editable. We'd prefer to give you an empty field back and let you pick a different value.

Differentiate between "bad record format" (i.e., we can't really do anything with this) and "bad record value" (i.e., everything is…