add missing testcase for stdClass

Author: simbig

tests/TicketSwapErrorFormatterTest.php

@@ -217,6 +217,13 @@ public static function provideHighlight() : iterable
             null,
             true
         ];
+        yield [
+            'Property <fg=yellow>App\Models\ExampleModel::$example_property</> (<fg=magenta>stdClass</>|<fg=magenta>null</>) does not accept <fg=magenta>mixed</>.',
+            'Property App\Models\ExampleModel::$example_property (stdClass|null) does not accept mixed.',
+            null,
+            null,
+            true,
+        ];
     }
 
     /**