My best recommendation for you is: building blocks.

Make a file building block that you can trust always, make one for your API, stop wasting your time writing the same thing over and over. Think about every problem once and fix it once and for all.

Noone will catch up to that, certainly not the novice who spend 80% of their time debugging code that fails for corner cases they don't understand.

Most of all, don't fix problems that cannot happen, such as wrong permissions.

If the permissions are wrong, something is already wrong and you should fix that rather than making your program bullet proof.

At some point you have to just not shoot yourself in the foot instead of always checking whether you did or not.

Instead of spending time on documentation, spend time making your code self-documenting and as short as possible. Replace all those duplicate-ish functions. Shrink your library, rename things with precision.