Inconsistent response handling in v2

Consider a request to a server that successfully returns XML data (aka anything that is not JSON).

In the node version we have this flow:

1. construct out as the concatenated data stream string
2. since the header content-type does not include application/json so...
3. the response data property is set to the out (aka the response body realized)
4. the promise is resolved with that response (aka response.data is the response body XML string)

However, in the fetch version we have this flow:

1. the header content-type does not include application/json so...
2. try to parse the string from fetch.text() as JSON
3. since the response is XML this throws
4. set the error on the response
5. the promise is rejected but the fetch.text() string is not available on the response

Compare the response handling in src/node.js and src/fetch.js, starting at the linked content-type branches and fetch.text() path. Trace how non-JSON response bodies are exposed and rejected, then verify that XML responses behave consistently in both implementations and that the body remains available when appropriate.