Using AI Model gpt-4.1, for user feedback: Modify\sCode\sto\sfix\sthis\serror\nSuccessfully\scompiled\sbut\sfailed\sat\sruntime.\n\nError\sAnalysis:\n*What\sFailed*:\sThe\stest\s`testUserWithNullUserIdThrowsException`\sexpected\sa\sNullPointerException\sbut\sinstead\sreceived\sa\sNumberFormatException.\n\n*Where*:\s`AppControllerGetDashboardTest.java:257`,\sin\s`AppController.getDashboard(AppController.java:45)`\n\n*Why*:\sA\snull\suser\sID\sis\sbeing\spassed\sand\sis\sattempted\sto\sbe\sparsed\sas\san\sinteger,\sthrowing\sNumberFormatException\srather\sthan\sNullPointerException.\n\n*Investigate*:\sUpdate\sthe\stest\sto\sexpect\sNumberFormatException,\sor\simprove\s`getDashboard`\sto\sexplicitly\shandle\snull\suser\sIDs\sbefore\sparsing.\sConsider\sinput\svalidation\sand\sclearer\serror\shandling.,