gem: Date::Error is not in Ruby 2.6 and older, use ArgumentError

lib/openvpn-status-web/parser/modern_stateless.rb

@@ -45,7 +45,7 @@ module OpenVPNStatusWeb
 
       private_class_method def self.parse_date(date_string)
         DateTime.strptime(date_string, '%a %b %d %k:%M:%S %Y')
-      rescue Date::Error
+      rescue ArgumentError
         DateTime.strptime(date_string, '%Y-%m-%d %k:%M:%S')
       end
     end