Hi there, as far as I know there isn't yet a way to handle globar error catching so It'll be hard to fullfil what you want. Maybe adding an event listener to the Application will help somehow.
Hi. You mention that you can't debug because the app is inside a web page. Could you clarify that? Do you mean you don't have access to the Flex source files and can't set a break point to trace it through the event cycle?
The application is deeply woven into the website it was created for, and requires parameters passed into it on initialization, a lot of AS - JS communication, and other things that make it difficult to just run in the Flex debugger without changing a lot of code just to find this issue.
I mean I CAN do it in the debugger, but it would probably take more time to set up for this than it would to hunt down the offending line of code that's causing the 1009 error in the first place! ;-)
Then there are tons of options for you:
FlashTracer FireFox plugin (shows traces for every SWF running on your computer).
FireBug FireFox plugin (you may have your SWF communicating with FireBug console).
All sorts of flash loggers based off the LocalConnection (DeMonster Debugger, XRay etc).
And, finally, you can use FlexBuilder's debugger to start a remote debugging session...
As long as you deploy a SWF that was built with -debug or -verbose-stacktraces, you don't even need a debugger. The player will display the line number of the place that hit the null object.
Flex SDK Developer
Adobe Systems Inc.