eca_form: Action "Entity form: build entity" may produce PHP warnings when the form contains a file upload widget
Problem/Motivation
Follow-up from #3323885: Inconsistent form field token syntax:
When a file upload widget is on a content entity form, then the action "Entity form: build entity" leads to a PHP warning error message.
Steps to reproduce
Proposed resolution
Fix the bug.
Remaining tasks
User interface changes
API changes
Data model changes
Edited by drupalbot