Eolian: Warn if iterator is NULL, set it to NULL after free

efl/eolian/__init__.pyx

@@ -148,10 +148,14 @@ cdef class EinaIterator(object):
             bint itr_ret
 
         if self.itr is NULL:
+            EINA_LOG_DOM_WARN(
+                EOLIAN_DOM, "Iterator is NULL!", NULL
+                )
             raise StopIteration
         itr_ret = eina_iterator_next(self.itr, &data)
         if not itr_ret:
             eina_iterator_free(self.itr)
+            self.itr = NULL
             raise StopIteration
 
         return void_ptr_to_python_obj(data, self.cls)