chore: major code cleanup and type safety using phpstan

src/Form/Service/Condition/RoomSelectionCondition.php

@@ -31,6 +31,10 @@ class RoomSelectionCondition implements FieldConditionInterface
      */
     public function __construct(array $requiredRoomCodes, string $matchMode = self::MATCH_MODE_PREFIX)
     {
+        if (!in_array($matchMode, [self::MATCH_MODE_PREFIX, self::MATCH_MODE_EXACT], true)) {
+            throw new \InvalidArgumentException(sprintf('Invalid match mode "%s".', $matchMode));
+        }
+
         $this->requiredRoomCodes = array_map('strtolower', $requiredRoomCodes);
         $this->matchMode = $matchMode;
     }