Throw an Error in async functions instead of returning an object

[besdar]

Hello @s0ftik3!

I noticed that in the asynchronous methods of the Reverso class, you return objects instead of throwing an error. As a result, the returned promise is resolved with an object that indicates an error occurred. In the event of an error in your code, it is better to throw an instance of the Error class.

After my changes it would be possible to use catch method of the Promise class, for example:

reverso.getContext(
    'meet me half way',
    'english',
    'russian',
).then(result => doMyStuff(result)).catch(err => handleError(err))

ref: https://javascript.info/async-await