Exit a language server if it sends a message with invalid json (#9332)

* Keep lsp event listener thread alive when malformed json is encountered from the lsp server

* Update unexpected error flow in recv() to close outstanding requests and close the language server

* Log malformed notifications as info instead of error

* Make close_language_server a nested function inside recv, similar to what's done in send

* Update malformed notification log text

* Clean up new log text a bit

* Initialize recv_buffer closer to where it's used

* Use "exit" instead of "close"

* Remove whitespace

* Remove the need for a helper method to exit the language server

* Match on Unhandled error explicitly and keep catch-all error case around

helix-lsp/src/transport.rs

@@ -270,7 +270,14 @@ impl Transport {
                         }
                     };
                 }
-                Err(Error::StreamClosed) => {
+                Err(err) => {
+                    if !matches!(err, Error::StreamClosed) {
+                        error!(
+                            "Exiting {} after unexpected error: {err:?}",
+                            &transport.name
+                        );
+                    }
+
                     // Close any outstanding requests.
                     for (id, tx) in transport.pending_requests.lock().await.drain() {
                         match tx.send(Err(Error::StreamClosed)).await {
@@ -300,10 +307,6 @@ impl Transport {
                     }
                     break;
                 }
-                Err(err) => {
-                    error!("{} err: <- {err:?}", transport.name);
-                    break;
-                }
             }
         }
     }

helix-term/src/application.rs

@@ -27,7 +27,7 @@ use crate::{
     ui::{self, overlay::overlaid},
 };
 
-use log::{debug, error, warn};
+use log::{debug, error, info, warn};
 #[cfg(not(feature = "integration"))]
 use std::io::stdout;
 use std::{collections::btree_map::Entry, io::stdin, path::Path, sync::Arc};
@@ -683,9 +683,13 @@ impl Application {
             Call::Notification(helix_lsp::jsonrpc::Notification { method, params, .. }) => {
                 let notification = match Notification::parse(&method, params) {
                     Ok(notification) => notification,
+                    Err(helix_lsp::Error::Unhandled) => {
+                        info!("Ignoring Unhandled notification from Language Server");
+                        return;
+                    }
                     Err(err) => {
-                        log::error!(
+                        error!(
-                            "received malformed notification from Language Server: {}",
+                            "Ignoring unknown notification from Language Server: {}",
                             err
                         );
                         return;