Failure example:
Reason why Ben code will crash is that he didnt anticipate to score at first roll 0 and on the second roll 10 (strike). Strike will casue error becouse it will actualize numer of roll by two (in that case should only actualize it by 1). This incorrect roll counter will lead to errors.
If someone can, please paste link to appropiate post in the Q&A about this.
Updated Thu Jul 05 2018 18:56
EDIT:
Ok, so in next chapters someone also mentioned this error. No need to duplicate this issue