Ticket #136: 79643f6e8c52.patch

lemon/list_graph.h

@@ -842 +842 @@
       explicit Arc(int pid) { id = pid;}
 
     public:
-      operator Edge() const { return edgeFromId(id / 2); }
+      operator Edge() const { 
+        return id != -1 ? edgeFromId(id / 2) : INVALID; 
+      }
 
       Arc() {}
       Arc (Invalid) { id = -1; }

lemon/smart_graph.h

@@ -465 +465 @@
       explicit Arc(int id) { _id = id;}
 
     public:
-      operator Edge() const { return edgeFromId(_id / 2); }
+      operator Edge() const { 
+        return _id != -1 ? edgeFromId(_id / 2) : INVALID; 
+      }
 
       Arc() {}
       Arc (Invalid) { _id = -1; }