#1
Do not fix your code.
Rather understand why nothing kept you from creating this bug. Make your code so easy that this bug would have been obvious the first time.
#2
Automate early.
You know, CI/CD. Or just clean-up-scripts. Or a complete infrastructure-as-code. Remember: A script to setup something is the best documentation!
#3
A function must not do more than one thing.
If a function name contains “and” there’s still work to do. Build small pieces.
#4
Side effects are the root of all evil.
If you need side effects (like database or file outputs), let it be the only thing a function does.
#5
It’s all about data.
Business logic is just a concept to change data.
#6
A system is defined by its input and output.
Every description of anything should focus on these two things first.