Problem Description

See #7025 (comment) for a traceback. HTTP/3 over QUIC works, but raw QUIC doesn't work here.

Steps to reproduce the behavior:

1. mitmdump --mode reverse:quic://http3.is@443
2. curl --http3-only https://http3.is -k -vvv --resolve http3.is:443:127.0.0.1

System Information

Mitmproxy: 11.0.0.dev (+47, commit e8db473)
Python:    3.12.3
OpenSSL:   OpenSSL 3.2.1 30 Jan 2024
Platform:  macOS-14.5-arm64-arm-64bit