Making a conditional check for type parser

The code is failing with pg-copy-streams.  The pg-copy-streams creates a query object but it doesn't have any _result.  Make the type parser an optional only when _result object available on query then only set the type parser.

Author: kesavkolla

lib/client.js

@@ -313,7 +313,9 @@ Client.prototype.query = function(config, values, callback) {
   if(this.binary && !query.binary) {
     query.binary = true;
   }
-  query._result._getTypeParser = this._types.getTypeParser.bind(this._types);
+  if(query._result) {
+    query._result._getTypeParser = this._types.getTypeParser.bind(this._types);
+  }
 
   this.queryQueue.push(query);
   this._pulseQueryQueue();