dbtest:demarshal() - Assert that the message is iterable, or things will go really bad down the line

Fixes static-scan warnings of this kind:

../../../dbind/dbtest.c:83:18: warning: The left operand of '==' is a garbage value [core.UndefinedBinaryOperatorResult]
    g_assert (v2 == 42);
              ~~ ^

1 files changed, 3 insertions, 0 deletions

diff --git a/dbind/dbtest.c b/dbind/dbtest.c
index 085d7ffb..511839c3 100644
--- a/dbind/dbtest.c
+++ b/dbind/dbtest.c
@@ -40,7 +40,10 @@ void demarshal (DBusMessage *msg, const char *type, void *ptr)
     DBusMessageIter iter;
 
     if (!dbus_message_iter_init (msg, &iter))
+      {
         fprintf (stderr, "no data in msg\n");
+        g_assert_not_reached ();
+      }
     else
         dbind_any_demarshal (&iter, &type, &ptr);
 }