Symfony 4 does not cast null to an empty array when loading the top-level YAML config anymore.
But the normalization creating a single default mailer in the prototyped node was not triggered when the top-level node was null. This now converts null to an empty array in the normalization logic.
Symfony 4 does not cast null to an empty array when loading the top-level YAML config anymore. But the normalization creating a single default mailer in the prototyped node was not triggered when the top-level node was null. This now converts null to an empty array in the normalization logic.
This makes tests green again.