dump is a Twig debugging function, like var_dump. You can pass
it any variable to print it out.
Refresh! For each field, you now see a giant list - for me, 27 things. All
of these are variables that you magically have access to inside a form theme
block. And the variables are the same no matter what block you’re in.
Remove the dump call. So we can finally use the errors variable in form_row
to only print the class if the field has errors: