Set Validation Error, empty value support for 2.0.x

Problem/Motivation

When adding an action for "Form Field : Set Validation Error", the help description indicates that an empty value is supported. It appears as if this is actually a required field that needs a value.

Steps to reproduce

Create a simple model that sets a validation error.

1. Event: Validate form -- I used node.article as a test.
2. Action: Set validation error; leave the "field name" blank.
3. Create article node. No validation error will be set.
4. Go back and add a field name in the action (e.g., body). Now attempting to the save the article sets the validation error.

This appears to have been fixed in 1.2.x but is still affecting 2.0.x.