Fix rename messages assuming having joined

src/network/Client.ts

@@ -29,6 +29,10 @@ export abstract class Client extends EventEmitter {
           this.metadata.name = data.newname;
         }
 
+        // Only mutate player list if we have one
+        // This is because rename messages can be received during the initial
+        // handshake, to signal a forced name change before joining.
+        if (this.players) {
           let idx = this.players.indexOf(data.oldname);
           if (idx < 0) {
             // Weird
@@ -39,6 +43,7 @@ export abstract class Client extends EventEmitter {
             break;
           }
           Vue.set(this.players, idx, data.newname);
+        }
         this.emit("rename", data.oldname, data.newname);
         break;
       // A new player joined the room (this includes us)