Avoid an unwrap when loading languages (#8562)

We couldn't reproduce the panic, but I believe it was possible when
uninstalling an extension while one if its grammars was still loading.

Release Notes:
- Fixed a crash that could happen when uninstalling a language extension
while its grammar was loading.

---------

Co-authored-by: Conrad <conrad@zed.dev>

crates/rpc/src/peer.rs

@@ -315,10 +315,13 @@ impl Peer {
                             "incoming response: requester resumed"
                         );
                     } else {
+                        let message_type = proto::build_typed_envelope(connection_id, incoming)
+                            .map(|p| p.payload_type_name());
                         tracing::warn!(
                             %connection_id,
                             message_id,
                             responding_to,
+                            message_type,
                             "incoming response: unknown request"
                         );
                     }