better axios error handler

[eviltik]

Ni !
hi @ndaidong

Thank you for your work.

I've forked your project, i'd like to improve error handling. Currently you return null on every axios errors.

What do you think about that ?

Making a PR right now

Thank you.

[Dong Nguyen]

@eviltik thank you, that's great! Please make pr and I will check it.