Fix PFL channel custom outputs.

src/mixer/audio.ts

@@ -188,6 +188,8 @@ class Player extends ((PlayerEmitter as unknown) as { new (): EventEmitter }) {
   }
 
   _connectPFL() {
+    // We check the existence of the analyser here, because if we're using a custom output, this won't exist.
+    if ((this.wavesurfer as any).backend.analyser) {
       if (this.pfl) {
         // In this case, we just want to route the player output to the headphones direct.
         // Tap it from analyser to avoid the player volume.
@@ -204,6 +206,7 @@ class Player extends ((PlayerEmitter as unknown) as { new (): EventEmitter }) {
         }
       }
     }
+  }
 
   public static create(
     engine: AudioEngine,