Fix a bug that cause UnhandledPromiseRejectionWarning on error

[SunriseFox]

#194

This PR tries to fix a bug that cause stray unhandled promises when runs on NodeJS app even if client.onerror is specified.

The cause is when IMAP close with an error, for example, Socket closed unexpectedly!, it will try clean _clientQueue and _currentCommand with the same error. However, _currentCommand's callback simply rejects the promise, but nowhere to catch the promise rejection or even find it without reading hundreds lines of the code. Problem code is here: client.js#L718

Simply swallow the rejection is safe, as the original code simply throws it without giving the user any chance to catch it.

This PR breaks the test as the same error will not be rejected twice. I think this behavior should be ok.

[SunriseFox]

Expected: all exceptions go through the onerror listener, if defined, no stray exceptions and no exception will be rejected twice. It may not be possible without rewriting a lot of parts of the code.

[jhoermann]

Any ideas why the test failed? Any chance that this will be pulled / pushed into master?

[SunriseFox]

Any ideas why the test failed? Any chance that this will be pulled / pushed into master?

Hey, if you'd like to use this workaround, you could try something like npm install SunriseFox/emailjs-imap-client#master (but I suggest that you fork it yourself in case that I may change this in the future.

[cormip]

Any progress on this fix?

2018-11-17 12:45:38-05:00(node:7) UnhandledPromiseRejectionWarning: Error: write after end
2018-11-17 12:45:38-05:00 at writeAfterEnd (_stream_writable.js:236:12)
2018-11-17 12:45:38-05:00 at TLSSocket.Writable.write (_stream_writable.js:287:5)
2018-11-17 12:45:38-05:00 at TLSSocket.Socket.write (net.js:707:40)
2018-11-17 12:45:38-05:00 at TCPSocket.send (/app/bundle/programs/server/npm/node_modules/emailjs-tcp-socket/dist/node-socket.js:129:20)
2018-11-17 12:45:38-05:00 at Imap.send (/app/bundle/programs/server/npm/node_modules/emailjs-imap-client/dist/imap.js:370:19)
2018-11-17 12:45:38-05:00 at Timeout._idleTimeout.setTimeout (/app/bundle/programs/server/npm/node_modules/emailjs-imap-client/dist/client.js:780:21)
2018-11-17 12:45:38-05:00 at ontimeout (timers.js:498:11)
2018-11-17 12:45:38-05:00 at tryOnTimeout (timers.js:323:5)
2018-11-17 12:45:38-05:00 at Timer.listOnTimeout (timers.js:290:5)
2018-11-17 12:45:38-05:00(node:7) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2261)