There appears to be a glitch in the game with Sideshow Bob. Occasionally when you start your game you will get a notification that Sideshow Bob has been spotted. If you manage to find him in your Springfield and tap him you’ll earn some money and XP. The problem is that this notification may also appear if you start your game and are taken directly to Krustyland. If you tap on him while he is roaming around Krustyland, your game will force quit.
Presumably the problem with this is that money doesn’t drop as a reward in Krustyland, tickets do. Sideshow Bob was not accommodated to drop tickets in the event he appeared in Krustyland. It is likely that when this glitch is fixed the notifications about Sideshow Bob being spotted will be strictly limited to the times you visit Springfield.
Do not worry about this glitch too much, all it is right now is inconvenient. If you tap on him in this scenario, the game will crash and you’ll have to launch it again, but everything will be fine when you resume play.