To change the icon-
-Navigate to your user's library folder by holding the option key while clicking on the "go" menu in finder, and selecting "Library"
-Navigate to the "Caches" folder
-Navigate to "com.apple.safari"
-Click on the "RemoteNotifications" folder
-Click on "web.com.xeeno.push" folder
-Click on the "Contents" folder
-Click on the "Resources" folder
Replace the icon with the one attached. This isn't the original icon, but it is one I created that looks identical. It should do the job until the issue is fixed.
Cheers