Fix: invalid error message when failed to delete user
Fix: invalid error message when failed to delete user

EduPepperPDTesting/pepper2013-testing,EduPepperPDTesting/pepper2013-testing,EduPepperPDTesting/pepper2013-testing,EduPepperPDTesting/pepper2013-testing,EduPepperPDTesting/pepper2013-testing,EduPepperPDTesting/pepper2013-testing