fix initial theme selection

src/main/java/com/sparrowwallet/sparrow/AppController.java

@@ -1020,8 +1020,10 @@ public class AppController implements Initializable {
     @Subscribe
     public void themeChanged(ThemeChangedEvent event) {
         String darkCss = getClass().getResource("darktheme.css").toExternalForm();
-        if(event.getTheme() == Theme.DARK && !tabs.getScene().getStylesheets().contains(darkCss)) {
+        if(event.getTheme() == Theme.DARK) {
-            tabs.getScene().getStylesheets().add(darkCss);
+            if(!tabs.getScene().getStylesheets().contains(darkCss)) {
+                tabs.getScene().getStylesheets().add(darkCss);
+            }
         } else {
             tabs.getScene().getStylesheets().remove(darkCss);
         }