Some compilers complain about 'control reaches end of non-void function'
because they don't understand that Py_FatalError() terminates the program.
diff --git a/Parser/grammar1.c b/Parser/grammar1.c
index 17e2ba9..440ba44 100644
--- a/Parser/grammar1.c
+++ b/Parser/grammar1.c
@@ -56,5 +56,6 @@
     }
     else {
         Py_FatalError("invalid label");
+        return NULL;
     }
 }