Storage.swf throws 13 runtime errors when exiting IE

[mpirnat]

When I have Storage.swf loaded in IE7 and enable showing alerts for all script errors, exiting the browser causes it to throw 13 runtime errors before exiting--one for each ExternalInterface? callback that was registered.

The runtime errors originate in the Flash plugin as it tries to delete the ExternalInterface? callbacks from the Flash object instance. It looks like something is causing the instance to be destroyed before the callbacks are cleaned up.

I've commented on http://bugs.adobe.com/jira/browse/SDK-14380 and filed https://bugs.adobe.com/jira/browse/FP-529 since I feel that this is buggy behavior in the Flash Player itself that could be a little bit smarter about its cleanup. However, it's been suggested that this may be an artifact of some onunload cleanup -- something causing the Flash object instance to be removed before the Flash Player plugin does its own cleanup.

For an example in the wild:

1. Launch IE7.

2. Enable alerts for all script errors.

3. Visit http://www.americangreetings.com/ecards/birthday

4. Exit the browser -- you should experience the storm of "A Runtime Error has occurred" alerts from "Line: 52" that say "Error: Object required".