fix(iframe): [PKG-IFRAME-03] release failed setup and bind message peers

packages/artplayer-tool-iframe/src/protocol.ts

@@ -0,0 +1,8 @@
+import type { Packet } from './requests'
+
+export function acceptsMessage(event: MessageEvent<unknown>, peer: Window | null): event is MessageEvent<Packet> {
+  if (event.source !== undefined && event.source !== null && event.source !== peer)
+    return false
+  const data = event.data
+  return typeof data === 'object' && data !== null && 'type' in data && typeof data.type === 'string'
+}