Domains, Logging, CLS, Exception Tracking, and monitoring systems like New Relic & NodeTime. There are many ways out there to identify problems and resolve them quickly. A great debugging process should start with identifying errors as soon as they happen, and give you the right information to swiftly resolve them.
We'll be trying out a new panel format. @danmactough, @necaris, and @Kimmelpalooza will answer our questions and tell some war stories while they're at it.