splitlist1.reverse(), like many list methods, acts in-place, and therefore returns None. So tobereversedlist1 is therefore None, hence the error.
You should pass splitlist1 directly:
splitlist1.reverse()
reversedlist = ‘ ‘.join(splitlist1)
string join must satisfy the connection object to be iterated(list, tuple)
splitlist1.reverse() returns None, None object not support iteration.