[gxml] SerializableObjectModel.desarialize remove warning

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit e6c12c404e74c03e9c5827073d719dbc037bd90b
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Mar 1 11:41:11 2017 -0600

    SerializableObjectModel.desarialize remove warning

 gxml/SerializableObjectModel.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gxml/SerializableObjectModel.vala b/gxml/SerializableObjectModel.vala
index 369dbf5..a34115d 100644
--- a/gxml/SerializableObjectModel.vala
+++ b/gxml/SerializableObjectModel.vala
@@ -307,7 +307,7 @@ public abstract class GXml.SerializableObjectModel : Object, Serializable
     Document doc;
     if (node is Document) {
       doc = (Document) node;
-      return_val_if_fail (doc.root != null, null);
+      return_val_if_fail (doc.root != null, false);
     }
     else
       doc = node.document;