The code isn't making assumptions, the programmer is.

That’s all the same. Then the code the programmer is writing is wrong because the programmer’s assumptions are wrong. Potato, potahto.

There's actually a fairly big difference with the context of the language preventing the error.

If the code is wrong as in undefined behavior, then the compiler can and maybe should try to prevent it. If the programmer is wrong about the code, then the compiler can't and definitely shouldn't try to prevent it.

In short, the compiler can't prevent this

  int is_empty(char* s) {
    return strlen(s) > 10;
  }

The compiler maybe could prevent this:

  is_empty(NULL);

Its not the same. The compiler can protect against code which is incorrect. The compiler cannot do anything to help with code that is correct but does the wrong thing.