Mage: Fix BC export when node is not associate.

src/Solver/Mage.py

@@ -268,6 +268,9 @@ class Mage(CommandLineSolver):
 
         for tab in ["liquid", "solid", "suspenssion"]:
             for bound in lst.get_tab(tab):
+                if bound.node is None:
+                    continue
+
                 if bound.bctype == "ZD":
                     AVA.append(bound)
                 elif bound.bctype == "TD" or bound.bctype == "PC":