nob_read_entire_dir with empty path string: segfault and different behavior on Windows

[ysoftware]

Following code leads to segfault

int main(int argc, char **argv) {
    Nob_File_Paths entries = {0};
    if (!nob_read_entire_dir("", &entries)) return 1;
    return 0;
}

Reason is incorrect check after opendir

dir->nob__private.posix_dir = opendir(dir_path);
if (dir == NULL) { ... return false; }

Must check the freshly returned value

if (dir->nob__private.posix_dir == NULL)

[ysoftware]

In the test that I added, I validated that with empty path nob_read_entire_dir will return false, but it seems to get triggered on Windows and fail the test.

It seems that on Windows passing empty string results in us searching in the root directory.

char *buffer = nob_temp_sprintf("%s\\*", dir_path);
results in \*
which maps to C:\* in my case.

I think at this point it must be decided, which behavior is more correct.