Field content doesn't show for invalid records

[vlad-ghita]

Probably same issue as:
bolt/redactor#28

Reproduce:

• Have custom ContentValidator returning a dummy ConstraintViolation
  eg: in bolt core source, change src/Validator/ContentValidator.php validate() method to:

    public function validate(Content $content)
    {
        $constraints = $this->getConstraints($content->getContentType());

        $constraints->add(new ConstraintViolation("zzz", null, [], null, null, null));

        return $constraints;
    }

• Have an Article field
• Populate Article field
• Save
• Upon reload, Article field value is not displayed.

Example form before save:

Example form after save: