[vala/0.46] g-i: Avoid use of uninitialized "markup" warning

[Rico Tzschichholz <ricotz src gnome org>]

commit 340620d0d9a1f0d5c2047775589895ed805ea108
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Tue Nov 5 15:34:52 2019 +0100

    g-i: Avoid use of uninitialized "markup" warning

 gobject-introspection/gidlwriter.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/gobject-introspection/gidlwriter.c b/gobject-introspection/gidlwriter.c
index 2c0cbaa5c..32c86f73d 100644
--- a/gobject-introspection/gidlwriter.c
+++ b/gobject-introspection/gidlwriter.c
@@ -273,6 +273,10 @@ interface_generate (GIdlWriter * writer, GIdlNodeInterface * node)
        ("<interface name=\"%s\" type-name=\"%s\" get-type=\"%s\">\n",
         node->node.name, node->gtype_name, node->gtype_init);
     }
+  else
+    {
+      g_assert_not_reached ();
+    }
 
   g_writer_write_indent (writer, markup);
   g_free (markup);