code: 'PROTOCOL_ENQUEUE_HANDSHAKE_TWICE',

[tunakaynar]

node:events:490
throw er; // Unhandled 'error' event
^

Error: Cannot enqueue Handshake after already enqueuing a Handshake.

[ashikjhonson]

I had the same problem, either
PROTOCOL_ENQUEUE_HANDSHAKE_TWICE or PROTOCOL_ENQUEUE_AFTER_QUIT
was displaying. Someone replied in another similar issue here, to remove the instance of connect() and end(), thankfully it worked for me.