Crash when delegate callback executed with NSError containing nil userInfo

[mdescalzo]

This callback crashes when the passed error has a nil userInfo object. According to Apple docs, this property is option, but it is required by the the current implementation:

- (void)session:(WCSession *)session didFinishUserInfoTransfer:(WCSessionUserInfoTransfer *)userInfoTransfer error:(NSError *)error

We ran into this with Apple Watches having connectivity issues resulting in errors.

[JP250552]

@mtford90 It looks like this was fixed by #120 and merged, but a new release was not created. Would you be able to create one please? Thank you!