Symfony version(s) affected: 4.3.1

Description
When a form is to be rendered, the following code in Twig runs:

{%- if translation_domain is same as(false) -%}               
{{- label -}}            
{%- else -%}
{{- label|trans(label_translation_parameters, translation_domain) -}}

By default translation_domain from validation "is not same as(false) ", which results in calling trans. Which in turn gives an exception

An exception has been thrown during the rendering of a template ("You cannot use the "Symfony\Bridge\Twig\Extension\TranslationExtension" if the Translation Contracts are not available. Try running "composer require symfony/translation".").

Trying to override translation_domain from validation implicitly enables validation and gives another error:

Validation support cannot be enabled as the Validator component is not installed. Try running "composer require symfony/validator".

How to reproduce
Try to render a Form without Translators and Validators

Possible Solution
translation_domain should be false if validation is disabled