fixed possible NPE

src/main/java/plugins/adufour/protocols/gui/block/WorkFlowPanel.java

@@ -331,12 +331,16 @@ public class WorkFlowPanel extends BlockPanel implements VarVisibilityListener
                                 if (blockDesc.isCollapsed())
                                     return;
 
-                                DragDropZone dz = varDropZones.get(variable);
-                                int y = dz.getLocationOnScreen().y;
-                                int offsetY = getLocationOnScreen().y;
+                                DragDropZone dz = getP1Zone();
+
+                                if (dz != null)
+                                {
+                                    int y = dz.getLocationOnScreen().y;
+                                    int offsetY = getLocationOnScreen().y;
 
-                                x1 = dz.getWidth();
-                                y1 = y - offsetY + dz.getHeight() / 2;
+                                    x1 = dz.getWidth();
+                                    y1 = y - offsetY + dz.getHeight() / 2;
+                                }
                             }
 
                             @Override

src/main/java/plugins/adufour/protocols/gui/link/Line.java

@@ -120,12 +120,12 @@ public abstract class Line extends Line2D.Float implements ComponentListener, Mo
 
         if (p1z != null)
             p1z.addMouseListener(this);
-        else
-            System.err.print("source drag zone null !");
+//        else
+//            System.err.print("source drag zone null !");
         if (p2z != null)
             p2z.addMouseListener(this);
-        else
-            System.err.print("destination drop zone null !");
+//        else
+//            System.err.print("destination drop zone null !");
     }
 
     /**