Calling createObject requires initialization, else we get an NPE.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6557 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/main/java/com/threerings/io/Streamer.java

@@ -536,6 +536,17 @@ public abstract class Streamer
             _writer = writer;
         }
 
+        @Override
+        public Object createObject (ObjectInputStream in)
+            throws IOException, ClassNotFoundException
+        {
+            // we need to initialize in order to access the constructor
+            if (_marshallers == null) {
+                initMarshallers();
+            }
+            return super.createObject(in);
+        }
+
         @Override
         public void writeObject (Object object, ObjectOutputStream out, boolean useWriter)
             throws IOException