Refactor: Add null handling to output directory selection

CityDoctorParent/Extensions/CityDoctorGUI/src/main/java/de/hft/stuttgart/citydoctor2/gui/CheckDialog.java

@@ -296,7 +296,14 @@ public class CheckDialog {
 
 		outputPathBtn.setOnAction(e -> {
 			DirectoryChooser directoryChooser = new DirectoryChooser();
-			outputPathTextField.setText(directoryChooser.showDialog(stage.getOwner()).getAbsolutePath());
+			directoryChooser.setInitialDirectory(Path.of(Settings.get(Settings.LAST_OPEN_FOLDER)).getParent().toFile());
+			File f = directoryChooser.showDialog(stage.getOwner());
+			if (f != null) {
+				outputPathTextField.setText(f.getAbsolutePath());
+				Settings.set(Settings.LAST_OPEN_FOLDER, f.getAbsolutePath());
+			}
+
+
 		});
 
 		streamCheckOption.setText(Localization.getText("CheckDialog.streamCheckOption"));