Error/quiz/attempterror

This error was found when testing for MDLQA-9267 in a local Windows 3.1 alpha server that did not have Cron configured:

• A student did not finish a quiz in the allowed time
• the student tried to continue the previous attempt, but without submitting the attempt before the grace period expired
• the quiz was recorded as Overdue
• after Cron runs, the quiz is correctly displayed as 'Never submitted'