cohttp-eio.Server: Don't blow up in callback
on client read timeout.
#1021
Failure
✅ (analysis) (passed)
✅ (lint-doc) (passed)
❌ (lint-fmt) (failed: Failed: Build failed)
❌ EXPERIMENTAL: (lint-opam) (failure: Failed: Build failed)
❌ EXPERIMENTAL: (lower-bound) (failure: Failed: Build failed)
✅ alpine-3.19-5.1_opam-2.1 (passed)
✅ debian-10-5.1_opam-2.1 (passed)
✅ debian-11-5.1_opam-2.1 (passed)
✅ debian-12-5.0_opam-2.1 (passed)
✅ debian-12-5.1+flambda_opam-2.1 (passed)
✅ debian-12-5.1_arm64_opam-2.1 (passed)
✅ debian-12-5.1_opam-2.1 (passed)
❌ debian-12-5.2~beta2_opam-2.1 (failed: Failed: Build failed)
✅ fedora-38-5.1_opam-2.1 (passed)
✅ fedora-39-5.1_opam-2.1 (passed)
✅ fedora-40-5.1_opam-2.1 (passed)
❌ EXPERIMENTAL: freebsd-5.1_opam-2.1 (failure: Failed: Build failed)
✅ macos-homebrew-5.1_arm64_opam-2.1 (passed)
✅ macos-homebrew-5.1_opam-2.1 (passed)
✅ opensuse-15.5-5.1_opam-2.1 (passed)
✅ ubuntu-20.04-5.1_opam-2.1 (passed)
✅ ubuntu-22.04-5.1_opam-2.1 (passed)
✅ ubuntu-23.04-5.1_opam-2.1 (passed)
✅ ubuntu-23.10-5.1_opam-2.1 (passed)