> "You can't debug something just by reading the code."
This is exactly how I debug things. When I first started working I was forbidden from using the debugger “you won’t have a debugger in the field”. Being able to read the code, spot the bug and tie it to the symptoms; that’s a skill. A damned important skill.
100%. Debuggers are nice when you can use them, trace logs are nice when you have them, clean repros are nice.
But lots of bugs can and should be found and fixed by inspection of the code, inspired by a reasonable observation.
Depending on your process needs, maybe write a test to confirm the fix.