Auto merge of #18066 - Veykril:lsp-server-no-panic, r=Veykril

fix: Don't panic lsp writer thread on dropped receiver

Should reduce the noise a bit (#18055). This removes the panic (and a follow up panic) when the server incorrectly shuts down, turning it into a proper late exit error.

lib/lsp-server/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lsp-server"
-version = "0.7.6"
+version = "0.7.7"
 description = "Generic LSP server scaffold."
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/rust-lang/rust-analyzer/tree/master/lib/lsp-server"

lib/lsp-server/src/stdio.rs

@@ -30,7 +30,9 @@ pub(crate) fn stdio_transport() -> (Sender<Message>, Receiver<Message>, IoThread
                 let is_exit = matches!(&msg, Message::Notification(n) if n.is_exit());
 
                 debug!("sending message {:#?}", msg);
-                reader_sender.send(msg).expect("receiver was dropped, failed to send a message");
+                if let Err(e) = reader_sender.send(msg) {
+                    return Err(io::Error::new(io::ErrorKind::Other, e));
+                }
 
                 if is_exit {
                     break;
@@ -60,15 +62,11 @@ impl IoThreads {
     pub fn join(self) -> io::Result<()> {
         match self.reader.join() {
             Ok(r) => r?,
-            Err(err) => {
-                println!("reader panicked!");
-                std::panic::panic_any(err)
-            }
+            Err(err) => std::panic::panic_any(err),
         }
         match self.writer.join() {
             Ok(r) => r,
             Err(err) => {
-                println!("writer panicked!");
                 std::panic::panic_any(err);
             }
         }