Error object missing from ErrorEvent in micro front-end architecture

I’m getting different ErrorEvents for the same error between Chrome and Firefox in my Micro Front-End project. My remote app can be accessed from the host’s domain or it’s own domain. When an error occurs the affected js files could be hosted by the host domain and the remote domain (CORS) . In Chrome I get the same error stack trace information whether I cause the error from the host domain (multiple domains are hosting the js files) or the remote’s domain (a single domain hosts the js files), in either case the ErrorEvent includes the error object, on issues. The js file are setup to allow CORS. In Firefox the ErrorEvent only includes the error object when I cause the error under remote domain (no CORS) , when the error is caused under the host domain (requires CORS) the ErrorEvent is missing the error object. I have CORS setup and Chrome is able to report errors across domains but Firefox cannot, why? Why would the ErrorEvent in FireFox be missing the Error object? BTW in the case where FireFox is missing the Error object in the ErrorEvent, the console was able to show the source files where the error occurred, it showed my TypeScript files, so FireFox is able to get source maps but for some reason that ErrorEvent is missing the Error Object. The Network tab shows 200s for all js and map files too.