Handle 504 response #502
Description
Default handling for unexpected response bodies (here)
has revealed an unhandled 504 response from intercom.
Example message from UnexpectedResponseError:
Intercom::UnexpectedResponseError, Expected a JSON response body.
Instead got '<html> <head><title>504 Gateway Time-out</title></head>
<body bgcolor="white"> <center><h1>504 Gateway Time-out</h1></center>
</body> </html> ' with status code '504'.