Fix progress dialog remaining on screen after load

This already happened in previous version without the recent changes.
There could be a race, where raw setVisible(false) call executes before
the initial invokeLater call to show it in the first place.

Author: Eswcvlad

src/main/java/com/itextpdf/rups/model/ObjectLoader.java

@@ -153,7 +153,7 @@ protected void done() {
         }
         try {
             eventListener.handleOpenDocument(this);
-            progress.setVisible(false);
+            SwingUtilities.invokeLater(() -> progress.setVisible(false));
         } catch (RuntimeException ex) {
             displayThrowable(ex);
         }
@@ -189,6 +189,6 @@ private void clearResult() {
     private void displayThrowable(Throwable th) {
         LoggerHelper.error(th.getLocalizedMessage(), th, getClass());
         progress.showErrorDialog(th);
-        progress.setVisible(false);
+        SwingUtilities.invokeLater(() -> progress.setVisible(false));
     }
 }