Cleanly handle missing stream error on COPY operation. Closes brianc#241

Author: Sandro Santilli

lib/query.js

@@ -170,9 +170,11 @@ p.prepare = function(connection) {
   this.getRows(connection);
 };
 p.streamData = function (connection) {
-  this.stream.startStreamingToConnection(connection);
+  if ( this.stream ) this.stream.startStreamingToConnection(connection);
+  else this.handleError(new Error('No destination stream defined'));
 };
 p.handleCopyFromChunk = function (chunk) {
-  this.stream.handleChunk(chunk);    
+  if ( this.stream ) this.stream.handleChunk(chunk);    
+  else this.handleError(new Error('error', 'No source stream defined'));
 }
 module.exports = Query;