frontend: arcade management rework

core/templates/widgets/err_banner.jinja

@@ -27,6 +27,10 @@ Access Denied
 Card already registered
 {% elif error == 13 %}
 AmusementIC Access Codes beginning with 5 must have IDm
+{% elif error == 14 %}
+Arcade does not exist
+{% elif error == 15 %}
+Some info failed to update
 {% else %}
 An unknown error occoured
 {% endif %}