[ax] Add new error types so that it’s easier to avoid crashing

[hieuk09]

Context

We make a few requests from one application to another application for each request. For example, we call Exit when user clicks on deactivate in TPS or Engage.

With those external requests, it's a good practice that we don't crash our application given another application crash. For the above example, if Exit crashes, TINYpulse shouldn't crash. It should simply return an error instead.

However, some errors, such as Curl::Err::ConnectionFailedError is bubbling up from TinyClient to TINYpulse. While we can certainly catch those errors in TINYpulse, it's better if TinyClient provides a generic error type so that we don't have to care about the internal implementation of TinyClient.

Change

This PR addresses the above problem:

• Creating a RequestError class to handle all errors related to making request. For example: if url is incorrect type, or not defined, or the internet connection is not up, ...
• Creating a BaseError so that we have a proxy to reference to all errors of TinyClient instead of having to refer to each error.

[dinhhuydh]

👍