Update logic

Author: Sparks29032

src/diffpy/morph/morphapp.py

@@ -410,8 +410,10 @@ def single_morph(parser, opts, pargs, stdout_flag=True, python_wrap=False):
         parser.error(
             "Too many arguments. Make sure you only supply FILE1 and FILE2."
         )
-    elif len(pargs) != 6 and not python_wrap:
-        parser.error("Python wrapper error.")
+    elif (len(pargs) != 2 or len(pargs) != 6) and python_wrap:
+        parser.error(
+            "Python wrapper error."
+        )
 
     # Get the PDFs
     # If we get from python, we may wrap, which has input size 4