Fixing a couple of NPEs

Change-Id: I19b5a2787b26e67e05640f6c64a13b58f2dc089a
diff --git a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
index df340a9..5b99105 100644
--- a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
+++ b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
@@ -564,6 +564,8 @@
 
     public void purgeEcmpGraph(DeviceId deviceId) {
         currentEcmpSpgMap.remove(deviceId);
-        updatedEcmpSpgMap.remove(deviceId);
+        if (updatedEcmpSpgMap != null) {
+            updatedEcmpSpgMap.remove(deviceId);
+        }
     }
 }