[shadowgovt]

> You should detect it based on the Content-Type header

In approximately a decade of working on JavaScript and TypeScript UI code, I can count on one hand the number of RPC handlers I've seen that inspect Content-Type in the success codepath.

... for that matter, I can count on one hand the number of RPC handlers I've see nthat inspect Content-Type in the failure codepath also. The common behavior is to dump body to text, log error, and recover.