Clone nationality presets so modifications don't fuck with the underlying global data

src/events/intro/customizeSlaveTrade/customizeSlaveTrade.js

@@ -372,7 +372,7 @@ App.UI.CustomSlaveTrade = function() {
 				App.UI.DOM.link(
 					name,
 					() => {
-						V.nationalities = nationalities;
+						V.nationalities = clone(nationalities);
 						refresh();
 					}
 				)