In order to avoid panics and garbled json responses, the main ServeHTTP request needs to know that the Stream operator is dead before continuing after a network close / timeout / request termination / assert failure.
Although there is no testcase, and code inspection has found nothing, if Stream fails to notify for whatever reason, this code path will lead to a hang, and there is at least one CBSE showing these symptoms.
Proactively find ways to remove this weakness, while not affecting throughput.

Symptoms include all the active requests stuck like this: