fix(mapper): handle non-backed enums in EnumCaster

Author: xHeaven

packages/mapper/src/Casters/EnumCaster.php

@@ -5,6 +5,7 @@
 namespace Tempest\Mapper\Casters;
 
 use Tempest\Mapper\Caster;
+use Tempest\Mapper\Exceptions\ValueCouldNotBeCast;
 use UnitEnum;
 
 final readonly class EnumCaster implements Caster
@@ -22,6 +23,10 @@ public function cast(mixed $input): ?object
             return null;
         }
 
+        if (!is_a($this->enum, \BackedEnum::class, allow_string: true)) {
+            return null;
+        }
+
         if (is_a($input, $this->enum)) {
             return $input;
         }