[Form] ChoiceType undefined index issue when using $resolver->setNormalizer('choices', #17270
Description
In 2.7.8 using setNormalizer to update 'choices' in a Form causes the below error:
CRITICAL - Uncaught PHP Exception Symfony\Component\Debug\Exception\ContextErrorException:
"Notice: Undefined index: Attribute 1" at
.../vendor/symfony/symfony/src/Symfony/Component/Form/Extension/Core/Type/ChoiceType.php line 288
A new fork has been created to show this issue. This can be found here.