potential nullptr dereference + use of uninitialized memory in fileutils

Bug report

Lines 2161 to 2162 in 6daf42b

     join_relfile(filename, bufsize, dirname, relfile);  
   return filename;  
 

can lead to use of uninitialized memory when join_relfile fails.

Lines 2197 to 2199 in 6daf42b

     _Py_normpath(wchar_t *path, Py_ssize_t size)  
   {  
   if (!path[0] || size == 0) {  
 

in combination with

Line 450 in 6daf42b

path2 = _Py_normpath(_Py_join_relfile(path, resolved), -1);

leads to a nullptr dereference.

	join_relfile(filename, bufsize, dirname, relfile);
	return filename;

	_Py_normpath(wchar_t *path, Py_ssize_t size)
	{
	if (!path[0] \|\| size == 0) {