TypeError: Cannot read property 'callback' of undefined

Error message detail:
C:\Users\xxxxx\node_modules\redis\index.js:722 if (typeof command_obj.callback === 'function') { ^ TypeError: Cannot read property 'callback' of undefined at normal_reply (C:\Users\xxxxx\node_modules\redis\index.js:722:28) at RedisClient.return_reply (C:\Users\xxxxx\node_modules\redis\index.js:824:9) at JavascriptRedisParser.returnReply (C:\Users\xxxxx\node_modules\redis\index.js:192:18) at JavascriptRedisParser.execute (C:\Users\xxxxx\node_modules\redis-parser\lib\parser.js:574:12) at Socket.<anonymous> (C:\Users\xxxxx\node_modules\redis\index.js:274:27) at Socket.emit (events.js:189:13) at addChunk (_stream_readable.js:284:12) at readableAddChunk (_stream_readable.js:265:11) at Socket.Readable.push (_stream_readable.js:220:10) at TCP.onStreamRead [as onread] (internal/stream_base_commons.js:94:17)

Source code of redis client:
function normal_reply (self, reply) { var command_obj = self.command_queue.shift(); if (typeof command_obj.callback === 'function') { if (command_obj.command !== 'exec') { reply = self.handle_reply(reply, command_obj.command, command_obj.buffer_args); } command_obj.callback(null, reply); } else { debug('No callback for reply'); } }
This error is happened occasionally, not all the time. I think maybe there's a bug, and should check command_obj when shift from comman queue.

Start in node_modules/redis/index.js at normal_reply and trace how self.command_queue is populated and shifted, using the reported stack trace as the entry point. Reproduce the intermittent failure if possible and verify that replies are handled safely when the queue state does not match the response; add or run a focused regression test if the repository provides one.