Hardware shutting down after an error message

This isn't as much a performance fail as a lowly bug, but it illustrates an important principle in an unexpected way.

Context

There was an embedded Qt project I was working on that didn't have any error propagation and display facilities. At some point, we were forced to add it to the system, and I had to write it. It wasn't very difficult, as it required reading and showing the error message in a modal error dialog.

Problem

After the Continuous Integration (CI) build's new release and the testers had installed...