Use assert and static_assert

[zakuArbor]

Purpose

Improve debugging by adding assert statements to limit the number of undefined behavior.

Also make more use of const on pointers and variables in function parameters

Tasks/Goals

• ensure username string length is not over the Linux defined length
• ensure length of file path does not exceed defined max length on Linux
• and more to be included ...

Summary

To fill out once the issue is to be closed. Give a short summary of the changes you made to implement or fix an issue