test(libSceSystemService): cover sceSystemServiceLaunchPlayerDialog with a null and an initialized param

Co-Authored-By: Claude Opus 5.5 <[email protected]>

core/libs/tests/GuestSystemService.cpp

@@ -52,6 +52,8 @@ void TestPlayerDialogParam() {
         threw = true;
     }
     Require(threw);
+    Require(sceSystemServiceLaunchPlayerDialog(nullptr) == SYSTEM_SERVICE_ERROR_PARAMETER);
+    Require(sceSystemServiceLaunchPlayerDialog(buffer) == SYSTEM_SERVICE_OK);
 }
 
 }