Improve error message if the command is not decodable
diff --git a/Modules/main.c b/Modules/main.c
index d129aba..a5c8905 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -275,6 +275,7 @@
     return ret != 0;
 
 error:
+    PySys_WriteStderr("Unable to decode the command from the command line:\n");
     PyErr_Print();
     return 1;
 }