x/net/quic: mishandling of ACK frames after space dropped

[neild]

If a single packet contains a CRYPTO frame which results in us dropping state for a packet number space, and contains a subsequent ACK frame, we will incorrectly close the connection with a protocol violation error. The CRYPTO frame drops state for the number space, and the ACK frame is then misinterpreted as acknowledging frames which were not sent.

[gopherbot]

Change https://go.dev/cl/634616 mentions this issue: quic: handle ACK frame in packet which drops number space