fix: Don't panic if nobody's listening

src/api/server/send.rs

@@ -214,9 +214,9 @@ fn fail_federation_txn(
 	services.transaction_ids.remove_federation_txn(txn_key);
 
 	// Send the error to any waiters
-	sender
-		.send(Some(Err(err)))
-		.expect("couldn't send error to channel");
+	if let Err(e) = sender.send(Some(Err(err))) {
+		debug_warn!("Failed to send transaction error to receivers: {e}");
+	}
 }
 
 /// Converts a TransactionError into an appropriate HTTP error response.

src/service/transaction_ids/mod.rs

@@ -11,6 +11,7 @@ use std::{
 use async_trait::async_trait;
 use conduwuit::{Error, Result, SyncRwLock, debug_warn, warn};
 use database::{Handle, Map};
+use futures::SinkExt;
 use ruma::{
 	DeviceId, OwnedServerName, OwnedTransactionId, TransactionId, UserId,
 	api::{
@@ -239,9 +240,9 @@ impl Service {
 			}),
 		);
 
-		sender
-			.send(Some(Ok(response)))
-			.expect("couldn't send response to channel");
+		if let Err(e) = sender.send(Some(Ok(response))) {
+			debug_warn!("Failed to send transaction response to waiting receivers: {e}");
+		}
 
 		// explicitly close
 		drop(sender);