Fixed opening file with null

src/gui/menubar/MenuBar.java

@@ -70,8 +70,11 @@ public class MenuBar extends JMenuBar{
 		openAction.addActionListener(new ActionListener() {
 			public void actionPerformed(ActionEvent arg0) {
 				try {
-					Agenda agenda = Io.readIo();
-					mainFrame.setAgenda(agenda);
+					Agenda agenda= Io.readIo();
+					if(Io.readIo() != null){
+						mainFrame.setAgenda(agenda);
+						System.out.println("read");
+					}
 				} catch (IOException e) {
 					e.printStackTrace();
 				}