Add some null checks that cause problems during unit tests
Add some null checks that cause problems during unit tests

JiboStore/couchbase-lite-net,couchbase/couchbase-lite-net,couchbase/couchbase-lite-net,couchbase/couchbase-lite-net,mpapp/couchbase-lite-net,brettharrisonzya/couchbase-lite-net,z000z/couchbase-lite-net,brettharrisonzya/couchbase-lite-net,JiboStore/couchbase-lite-net,mpapp/couchbase-lite-net,z000z/couchbase-lite-net