Avoid NetworkGraph commit() if newSwitch() failed to create NetworkGraph vertex.
diff --git a/src/main/java/net/onrc/onos/ofcontroller/core/internal/SwitchStorageImpl.java b/src/main/java/net/onrc/onos/ofcontroller/core/internal/SwitchStorageImpl.java
index 03a5e8e..126efb3 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/core/internal/SwitchStorageImpl.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/core/internal/SwitchStorageImpl.java
@@ -72,7 +72,8 @@
 		
 		log.info("SwitchStorage:addSwitch(): dpid {} ", dpid);
 		try {
-			newSwitch(dpid);
+			ISwitchObject sw = newSwitch(dpid);
+			if ( sw == null ) throw new RuntimeException();
             op.commit();
 		} catch (Exception e) {
 			e.printStackTrace();