[java-atk-wrapper] Fix null dereference

[Samuel Thibault <sthibaul src gnome org>]

commit 166a56cb02ee85a7ad1301974ef10d949173bfe8
Author: Samuel Thibault <samuel thibault ens-lyon org>
Date:   Sat Jul 27 21:04:36 2019 +0200

    Fix null dereference

 wrapper/org/GNOME/Accessibility/AtkComponent.java | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/wrapper/org/GNOME/Accessibility/AtkComponent.java 
b/wrapper/org/GNOME/Accessibility/AtkComponent.java
index 010e130..b0cf883 100644
--- a/wrapper/org/GNOME/Accessibility/AtkComponent.java
+++ b/wrapper/org/GNOME/Accessibility/AtkComponent.java
@@ -138,6 +138,8 @@ public class AtkComponent {
             if(acc_component.isVisible()){
                 Rectangle rect = acc_component.getBounds();
                 Point p = acc_component.getLocationOnScreen();
+                if (rect == null || p == null)
+                    return null;
                 rect.x = p.x;
                 rect.y = p.y;
                 return rect;