chore: Fixes issue related to flow types (#4724)

* Fixes issue related to flow types

* Improves type inference on where clause, index

* run parse-server start on liveQueryServer only on mongo, state leaks on postgres

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -161,7 +161,7 @@ export class MongoStorageAdapter implements StorageAdapter {
     return this.connectionPromise;
   }
 
-  handleError<T>(error: ?Error): Promise<T> {
+  handleError<T>(error: ?(Error | Parse.Error)): Promise<T> {
     if (error && error.code === 13) { // Unauthorized error
       delete this.client;
       delete this.database;