Robustness issue in responses to 'request-input' events

[Omikhleia]

Sort of similar to #171, but for 'request-input' socket events (necessarily requiring a mis-behaving client, so in a sense 'less problematic').

Monkey testing.

Case 1 - Character selection:
A mis-behaving client can crash the game by providing a null or non-string selection.

TypeError: selection.toLowerCase is not a function
    at Socket.emit (...room.js-server\src\controllers\user-controller.js:107:52)

Case 2 - Login, password issue
A mis-behaving client can crash the game by providing a null, undefined or non-string password.

Null password:

TypeError: Cannot read property 'length' of null
    at Pbkdf2.checkPassword (...room.js-server\src\lib\pbkdf2.js:66:26)
    at Socket.emit (...src\controllers\unauthenticated-user-controller.js:94:14)

Non-string password, here an integer:

TypeError: Pass phrase must be a buffer
    at TypeError (native)
    at pbkdf2 (crypto.js:575:20)
    at Object.exports.pbkdf2 (crypto.js:557:10)
    at Pbkdf2.checkPassword (...room.js-server\src\lib\pbkdf2.js:79:12)
    at Socket.emit (...src\controllers\unauthenticated-user-controller.js:94:14)

Case 3 - Login, username issue
A mis-behaving client can crash the game by providing a null, undefined or non-string username.

Null username:

TypeError: Cannot read property 'trim' of null
    at Socket.emit (...src\controllers\unauthenticated-user-controller.js:86:41)

Non-string password, here an integer:

TypeError: username.trim is not a function
    at Socket.emit (...src\controllers\unauthenticated-user-controller.js:86:42)

Case 4 - Create (account creation), username issue
A mis-behaving client can crash the game by providing a null, undefined or non-string username. Same error signatures as previous case, just differing by line numbers.

For a null:

TypeError: Cannot read property 'trim' of null
    at Socket.emit (...src\controllers\unauthenticated-user-controller.js:36:41)

And 36:42 for a non-string (tested with integer), on username.trim too.

Case 5 - Create (account creation), password issue
Username is assumed to be valid and non-existent.
With password = password2= null:

TypeError: Cannot read property 'length' of null
    at Pbkdf2.hashPassword (...room.js-server\src\lib\pbkdf2.js:36:26)
    at Socket.emit (...src\controllers\unauthenticated-user-controller.js:49:14)

And with integer:

TypeError: Pass phrase must be a buffer
    at TypeError (native)
    at pbkdf2 (crypto.js:575:20)
    at Object.exports.pbkdf2 (crypto.js:557:10)
    at Pbkdf2.hashPassword (...room.js-server\src\lib\pbkdf2.js:43:12)
    at Socket.emit (..src\controllers\unauthenticated-user-controller.js:49:14)

Case 6 - Create (character creation), player name issue
Similar issues.
I just threw an empty object {} as response, here, to test with undefined.

TypeError: Cannot read property 'replace' of undefined.
    at Socket.emit (...room.js-server\src\controllers\user-controller.js:53:72)

Doh, feeling like a true monkey... Why haven't I automated those tests ? ':|