From f15f2bc788bfb4d709fa59fc221da8dce734a71b Mon Sep 17 00:00:00 2001
From: hneemann <helmut.neemann@arcor.de>
Date: Fri, 7 Apr 2017 13:01:29 +0200
Subject: [PATCH] fixed an error if nets in nested circuits are merged via a
 direct nested connection

---
 src/main/java/de/neemann/digital/draw/model/Net.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/main/java/de/neemann/digital/draw/model/Net.java b/src/main/java/de/neemann/digital/draw/model/Net.java
index 096f394e6..7ca45bcec 100644
--- a/src/main/java/de/neemann/digital/draw/model/Net.java
+++ b/src/main/java/de/neemann/digital/draw/model/Net.java
@@ -121,7 +121,8 @@ public class Net {
      */
     public void addNet(Net otherNet) {
         pins.addAll(otherNet.getPins());
-        wires.addAll(otherNet.getWires());
+        if (wires != null && otherNet.getWires() != null)
+            wires.addAll(otherNet.getWires());
         labelSet.addAll(otherNet.labelSet);
     }