Errors that should NOT count as B2 service failures.
Client-side 4xx (except 408 and 429) reflect bad requests, not B2 trouble.
Caller cancellations are also filtered so client disconnects cannot open a
shared B2 circuit breaker.
Exported for direct testing.
Parameters
err: unknown
Returns boolean
True when the error should be filtered out of breaker failures.
Errors that should NOT count as B2 service failures. Client-side 4xx (except 408 and 429) reflect bad requests, not B2 trouble. Caller cancellations are also filtered so client disconnects cannot open a shared B2 circuit breaker. Exported for direct testing.