docs: update error documentation (#6648)

Correctly pass the event.detail to the error handler instead of the event

docs/tutorials/errors.md

@@ -21,7 +21,7 @@ const player = new shaka.Player();
 await player.attach(video);
 
 // handle errors that occur after load
-player.addEventListener('error', handleError);
+player.addEventListener('error', (event) = handleError(event.detail));
 
 // there are two options for catching errors that occur during load