Server with IPv6 enabled, but domain has no AAAA record throws an error

[Noodleyman]

If the web server on which the sites are hosted has IPv6 support, but the domain using Stripe itself has no AAAA DNS record, then the library CURL request can fail with error:

Uncaught (in promise) SyntaxError: Unexpected end of JSON input

to work around it, I forced the CURL request in CurlClient.php to use IPv4 only, however ideally this should be handled better with IPv6 detection an AAAA record validation.

I consider this an edge case, although with IPv6 becoming more common, I've seen this catch out at least two stores which depend on this library. both required the adjustment to force IPv4 use (or, both could also have been setup for IPv6 properly).