Check if Error object has stack property. Fixes #34.

[robertoschiavone]

This PR addresses the problem described in #34

When trying to log an Error with an undefined stack trace, now signale correctly logs the error name and ignores the stack property.

Before:

const [name, ...rest] = msg.stack.split('\n');
                                        ^
TypeError: Cannot read property 'split' of undefined

After:

✖  error     SyntaxError

[passcod]

If you .toString() the error instead, and replace the missing stack with that, it avoids losing so much information.

[klaudiosinani]

Nice approach! We could also rely upon type conversion and prevent any falsy value from making it through, that way rare cases where stack is set, for example, to null are covered too;

if (msg instanceof Error && msg.stack) {

[klaudiosinani]

A minor tweak and it is good to go! Thank you for taking the time to contribute : )

[robertoschiavone]

@passcod can you provide an example of that? I tried to reproduce your .toString() suggestion but I obtained the exact same results.

Obviously this is the smallest tweak ever committed, so I guess that any further improvement would be welcome.

[klaudiosinani]

Thank you!

[passcod]

@robertoschiavone ah, nevermind, yes you're correct. Thanks for the PR :)