What does debugging a program look like?

To get closer to the dream of “every single time there’s an error, the program reports to you exactly what happened in an easy to understand way” you also need to be disciplined about immediately returning an error message instead of silently writing incorrect data / passing a nonsense value to another function which will do WHO KNOWS WHAT with it and cause you a gigantic headache. One sub debugging skill that I take for granted a lot of the time is understanding what error messages mean! And a lot of the time error messages are caused by a problem very different from the text of the message, like how “upstream connect error or disconnect/reset before headers” might mean “julia, your server crashed!

Source: jvns.ca