BUG/MINOR: quic: fix segfault on CC if mux uninitialized

A segfault happens when receiving a CONNECTION_CLOSE during handshake.
This is because the mux is not initialized at this stage but the
transport layer dereferences it.

Fix this by ensuring that the MUX is initialized before. Thanks to Willy
for his help on this one. Welcome in the QUIC-men team !
1 file changed