[Form][BUG]Button missing getErrorsAsString() fixes #8084
Debug: Not calling undefined method anymore.
If the form contained a submit button the call would fail and the debug of the form wasn't possible.
Now it will work in all cases.
This fixes #8084
Merge branch 'patch-1' of https://github.com/mikeSimonson/symfony into patch-1

Conflicts:
	src/Symfony/Component/Form/Form.php