CL-7765 Updated the pay-client code to handle the callback & un-promised rejections

[tusharpari]

1. Handled the callback param in request method
2. Added try catch block to handle the un-promised rejections

[antigenius]

Please add tests to cover the next callback functionality that's been added. Additionally, there don't appear to be any Travis CI steps in place. I would like you to confirm that all tests are passing once the above test has been added. Thank you.

[antigenius]

You can remove this else and just have the return statement. Many style guides prefer this method.

[aakolkarclassy]

Updated the code.

[timothyk7]

same as matt said

[antigenius]

@aakolkarclassy I've been trying to resolve the bug we discussed the other day as your latest commit will introduce errors later (the value of reponseObj.count is used to iterate across paginated results from the API. However, I'm now not sure this commit is even necessary. I believe @tusharpari is out on leave, but do you or anyone else know why we need this functionality? @timothyk7, do you recall why the callback functionality was needed?

Tushar had said there was a need to supply a callback to the request method in order to migrate from ClassyPay Client to ClassyPay Core. However, the request method is private, and none of the public methods in the class supply a callback. It appears that extra arguments were added to some method signatures and a conditional to use the callback if provided. However, after taking a closer look at the changes, I don't believe any of that code will ever be used.

Unless someone knows why we need this, I'd like to decline this PR.

[timothyk7]

@aakolkarclassy I've been trying to resolve the bug we discussed the other day as your latest commit will introduce errors later (the value of reponseObj.count is used to iterate across paginated results from the API. However, I'm now not sure this commit is even necessary. I believe @tusharpari is out on leave, but do you or anyone else know why we need this functionality? @timothyk7, do you recall why the callback functionality was needed?

Tushar had said there was a need to supply a callback to the request method in order to migrate from ClassyPay Client to ClassyPay Core. However, the request method is private, and none of the public methods in the class supply a callback. It appears that extra arguments were added to some method signatures and a conditional to use the callback if provided. However, after taking a closer look at the changes, I don't believe any of that code will ever be used.

Unless someone knows why we need this, I'd like to decline this PR.

all I know it was needed for classyql for the callback

[antigenius]

Please close in favor of https://github.com/classy-org/classyql/pull/435