One jammed tablet silenced two screens

transcript

A restaurant tablet's printer jams. It throws an error. And two other screens never hear about the order. Not the customer. Not the rider.

The order calls its listeners one by one. In a plain loop. The tablet is first. It throws. The error leaves the loop. The others are never called. They never hear.

Without a catch, the customer sees no update. Neither does the rider. With a catch around each listener, both screens update. Even with the tablet broken. And the failure is recorded, not lost.

Catch per listener. Then don't hide the error. Silence is its own bug. Log it, count it, or return it to the caller. Then carry on with the next listener. The customer and the rider still hear.

A broken screen is its own problem. Record it, and move on. It must never decide who else finds out. That is the rule.

Full breakdown in the lecture.