http: superfluous response.WriteHeader under load

[lidel]

Error from https://github.com/ipfs/kubo/pull/7165 (or its variant) seems to be back if a node is under some gateway load.

kubo-staging-us-east-02 running kubo v0.33.0-rc1 (https://github.com/ipfs/kubo/issues/10580) with boxo v0.26.0 has a lot of these in logs:

Dec 21 05:06:58 kubo-staging-us-east-02 ipfs[488049]: 2024/12/21 05:06:58 http: superfluous response.WriteHeader call from github.com/prometheus/client_golang/prometheus/promhttp.(*responseWriterDelegator).WriteHeader (delegator.go:65)

Did not investigate the source of this one, but it is likely one of http handlers (rpc api, gateway, prometheus metrix exporter?)