fix(signalling): do not crash when a forced subscription is declined (#958) (#969)

* fix(signalling): do not crash when a forced subscription is declined

sendToStreamer() force-subscribes a player that sends a message while
unsubscribed, then forwards the message through non-null assertions on
subscribedStreamer. subscribe() can decline - most commonly because
maxSubscribers is already reached - and signals that only by leaving
subscribedStreamer unset, so the assertions throw a TypeError out of a
websocket message handler and bring the whole process down with them,
disconnecting every other player.

This is easiest to hit at --max_players 1, where the second player to
send anything is by definition over the limit.

Check the subscription took and disconnect that one player if it did
not, which is what the branch above already does when there is no
streamer to subscribe to at all.

* chore: declare wilbur in the forced-subscribe crash changeset

The fix ships to operators as Wilbur, so name it in the changeset rather
than letting it land as a bare "updated dependencies" entry. Matches the
two most recent Signalling changesets, which both list it alongside the
library.

---------


(cherry picked from commit c6e78fb)

Co-authored-by: marekl11 <55535563+marekl11@users.noreply.github.com>

Author: mcottontensor

.changeset/player-forced-subscribe-crash.md

@@ -0,0 +1,6 @@
+---
+'@epicgames-ps/lib-pixelstreamingsignalling-ue5.8': patch
+'@epicgames-ps/wilbur': patch
+---
+
+Stop an unsubscribed player from crashing the signalling server. When a player sends a message without being subscribed, `sendToStreamer` force-subscribes it to the first available streamer and then forwards through `this.subscribedStreamer!`. `subscribe()` can decline — most commonly because `maxSubscribers` is already reached — and reports that only by leaving `subscribedStreamer` unset, so the non-null assertions throw a TypeError out of a websocket message handler and take the process down, disconnecting every other player. It now checks the subscription took, and disconnects just that player if it did not.

Signalling/src/PlayerConnection.ts

@@ -142,12 +142,22 @@ export class PlayerConnection implements IPlayer, LogUtils.IMessageLogger {
             } else {
                 Logger.warn(`Subscribing to ${streamerId}`);
                 this.subscribe(streamerId);
+                // subscribe() declines silently, most often because maxSubscribers is reached, and
+                // says so only by leaving subscribedStreamer unset. Forwarding anyway dereferences
+                // null, which surfaces as an uncaughtException and exits the process.
+                if (!this.subscribedStreamer) {
+                    Logger.error(
+                        `Player ${this.playerId} could not be subscribed to ${streamerId}. Disconnecting.`
+                    );
+                    this.disconnect();
+                    return;
+                }
             }
         }
 
         message.playerId = this.playerId;
-        LogUtils.logForward(this, this.subscribedStreamer!, message);
-        this.subscribedStreamer!.protocol.sendMessage(message);
+        LogUtils.logForward(this, this.subscribedStreamer, message);
+        this.subscribedStreamer.protocol.sendMessage(message);
     }
 
     private subscribe(streamerId: string) {