Optional arguments passed to the SMTP object do result in a throw if undefined is passed

[SanderDeWaal1992]

When I omit for example the 'timeout' option, it works ok. If I set timeout to be undefined, it does throw:

// Does go well:
emailJs.server.connect({
	user: "username",
	password: "password",
	host: "127.0.0.1",
	port: 1234
});
// Does not go well:
// Will throw  `The "msecs" argument must be of type number. Received type undefined`
emailJs.server.connect({
	user: "username",
	password: "password",
	host: "127.0.0.1",
	port: 1234,
	timeout: undefined
});

This problem occurs since version 2.1.0. Version 2.0.0 did work as expected.

Expected behavior

both of above code snippets should work the same way.

[zackschuster]

@SanderDeWaal1992 this is due to some faulty logic with the Object.assign call in the SMTP constructor. i've put up a PR to fix this.