Improve args check to support optional params for makeRequest

[cjavilla-stripe]

I ran out of time trying to write an automated test for this. I'm not familiar with this nock tooling and was able to get past the root error and my basic test passing locally. Also, didn't see a compact helper so just used this filter.

This is to address #825

(async () => {
  const id = 'acct_1GBs7XDllkSPMYqA';
  const account = await stripe.accounts.retrieve(id)
  console.log(account)
  const account2 = await stripe.accounts.retrieve(id, undefined)
  console.log(account2)
})();

r? @rattrayalex-stripe
cc @stripe/api-libraries

[rattrayalex-stripe]

Thanks, I think this looks good! I do think we should try to get a test in there for it, added time to pair on this.

A tiny nit is that I much prefer == null for nullish (null/undefined) testing.

ptal @cjavilla-stripe