🐛 Fix serialization of missing values

[DRSchlaubi]

traewelling/app/Http/Resources/OperatorResource.php

Lines 49 to 54 in 9fbb1c0

	'identifier' => $this->when( // @deprecated: remove after 2026-09
	$this->relationLoaded('identifiers'),
	fn () => $this->identifiers->firstWhere('type', 'hafas')?->identifier
	),
	'name' => $this->name,
	'identifiers' => $this->whenLoaded('identifiers', fn () => OperatorIdentifierResource::collection($this->identifiers)),

Some functions like when returned MissingValue directly causing invalid json being rendered

#HSFDPMUW