firefox RR: make errors non-fatal

apps/Firefox Rapid Release/uninstall

@@ -7,8 +7,8 @@ function error {
   exit 1
 }
 
-sudo apt purge firefox -y || error "Failed to uninstall firefox!"
+sudo apt purge firefox -y
-sudo rm /etc/apt/preferences.d/99bionic-updates || error "Failed to delete /etc/apt/preferences.d/99bionic-updates"
+sudo rm -f /etc/apt/preferences.d/99bionic-updates
-sudo rm /etc/apt/sources.list.d/firefox-ubuntu.list || error "Failed to delete the repository!"
+sudo rm -f /etc/apt/sources.list.d/firefox-ubuntu.list
 sudo apt-key del "3B4FE6ACC0B21F32" || error "Failed to delete the key!"