Firefox installation error - options_page

[OranShuster]

Cannot install 2.0.1 on FF57 or FF58 (beta)
installing the addon in debug mode shows the following error
Reading manifest: Error processing options_page: An unexpected property was found in the WebExtension manifest.

there is options_ui which is compatible with firefox but it appears that it will not accept the options_page entry

[pd4d10]

options_page is for old version Chrome compatibility, see:

https://developer.chrome.com/extensions/optionsV2#migration

Firefox will show this warning, but you can still use it.

Maybe we can release a different zip for Firefox to remove this warning later.

Thanks!