Merge branch 'mkirk/avoid-deadlock-on-unknown-session'

src/Messages/TSMessagesManager.m

@@ -337,12 +337,13 @@ NS_ASSUME_NONNULL_BEGIN
         int deviceId = messageEnvelope.sourceDevice;
         dispatch_async([OWSDispatch sessionStoreQueue], ^{
             if (![storageManager containsSession:recipientId deviceId:deviceId]) {
+                __block TSErrorMessage *errorMessage;
                 [self.dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-                    TSErrorMessage *errorMessage =
+                    errorMessage =
                         [TSErrorMessage missingSessionWithEnvelope:messageEnvelope withTransaction:transaction];
                     [errorMessage saveWithTransaction:transaction];
-                    [self notififyForErrorMessage:errorMessage withEnvelope:messageEnvelope];
                 }];
+                [self notififyForErrorMessage:errorMessage withEnvelope:messageEnvelope];
                 DDLogError(@"Skipping message envelope for unknown session.");
                 completion(nil);
                 return;