fix: guard unknown event types, keep world.t consistent on throw (review)

src/sim/world.js

@@ -82,10 +82,15 @@ const HANDLERS = {
 
 // Advance the world to absolute time toTime, processing all due events in order.
 export function advance(world, toTime) {
+  try {
     while (world.queue.size > 0 && world.queue.peek().time <= toTime) {
       const ev = world.queue.pop();
       world.t = ev.time;
-    HANDLERS[ev.type](world, ev.data);
+      const handler = HANDLERS[ev.type];
+      if (!handler) throw new Error(`Unknown event type: ${ev.type}`);
+      handler(world, ev.data);
     }
+  } finally {
     world.t = toTime;
   }
+}