fix theme loading

src/gui/theming.js

@@ -82,7 +82,7 @@ App.UI.Theme = (function() {
 		theme.setAttribute("type", "text/css");
 		theme.setAttribute("href", `./${filename}`);
 		// make it unique to force reloading instead of using the cached version
-		devTheme.href += `?id=${Date.now()}`;
+		theme.href += `?id=${Date.now()}`;
 		document.head.appendChild(theme);
 		return theme;
 	}