Fixes invalidate nextid

Change-Id: I475899566fcd2a51dd7d0e672ede6e65e25c8f78
diff --git a/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java b/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java
index e46c1d8..8c4968a 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java
@@ -1240,7 +1240,8 @@
                 (objective, error) -> {
                     log.warn("Failed to add {} on {}/{}, vlan {}: {}",
                             mcastIp, deviceId, port.toLong(), assignedVlan, error);
-                    srManager.invalidateNextObj(objective.id());
+                    // Schedule the removal using directly the key
+                    mcastWorker.execute(() -> mcastNextObjStore.remove(mcastStoreKey));
                 });
             ForwardingObjective fwdObj = mcastUtils.fwdObjBuilder(mcastIp, assignedVlan,
                                                           newNextObj.id()).add(context);