Using assertions in NCC library functions

[thass0]

Some C library functions don't allow their pointer arguments to be NULL (e.g. strtoks delimiter argument). In case of glibc, they respond to NULL by crashing with a segfault. For debugging purposes, and to make it easier to reason about segfaults, it would be beneficial if they called assert(x != NULL) instead.
The downside of adding assertions to frequently called functions might be that the performance is slightly worse. At the time of writing this, there are a few assertions found in /include/uvm already.

In general, should assertions be added to library functions that have certain constraints like requiring pointers to not be NULL?

[maximecb]

Yes I think we should add assertions. I don't expect string functions to be super performance-sensitive, and in theory we can eliminate all the overhead of all assertions by compiling code in release mode.

[thass0]

Yes, I agree.