When calling:
action.setIcon({path: null})
A web extension requests the browser to restore the action icon to the in the manifest specified icon in action.default_icon. However, currently it falls back to manifest.icons.
This may break firefox extensions when installed in Orion.
To restore to the icons specified in manifest.action.default_icon
Version 0.99.138-beta (WebKit 623.1.8.0.0)
Tahoe (26)