CLOUDSTACK-9691: Fixed unhandeled excetion in list snapshot command when

a primary store is deleted related to it

Author: anshul-gangwar

server/src/com/cloud/api/ApiResponseHelper.java

@@ -527,6 +527,9 @@ public static DataStoreRole getDataStoreRole(Snapshot snapshot, SnapshotDataStor
 
         long storagePoolId = snapshotStore.getDataStoreId();
         DataStore dataStore = dataStoreMgr.getDataStore(storagePoolId, DataStoreRole.Primary);
+        if (dataStore == null) {
+            return DataStoreRole.Image;
+        }
 
         Map<String, String> mapCapabilities = dataStore.getDriver().getCapabilities();