[kazinator]

If a bug happens because you didn't test, you should feel guilty.

Do everything you're supposed to do as a software engineer; then you won't feel guilty about the remaining bugs that slip through.

Also, don't feel too guilty if you break something which someone else developed that wasn't (1) documented and (2) covered by regression tests to catch the breakage.

When users report a bug, don't feel guilty if they are relying on some undocumented behavior, and it's not working they way they imagine. (Of course, security, reliability and robustness to bad inputs shouldn't have to be documented; that's not what my remark here is about.)