Disabling choices when they are computed incorrectly.

src/base/abc/abcCheck.c

@@ -177,7 +177,10 @@ int Abc_NtkDoCheck( Abc_Ntk_t * pNtk )
 
     // check the nodes
     if ( Abc_NtkIsStrash(pNtk) )
-        Abc_AigCheck( (Abc_Aig_t *)pNtk->pManFunc );
+    {
+        if ( !Abc_AigCheck( (Abc_Aig_t *)pNtk->pManFunc ) )
+            return 0;
+    }
     else
     {
         Abc_NtkForEachNode( pNtk, pNode, i )

src/base/abci/abcDar.c

@@ -1204,7 +1204,11 @@ Abc_Ntk_t * Abc_NtkFromDarChoices( Abc_Ntk_t * pNtkOld, Aig_Man_t * pMan )
     Aig_ManForEachCo( pMan, pObj, i )
         Abc_ObjAddFanin( Abc_NtkCo(pNtkNew, i), (Abc_Obj_t *)Aig_ObjChild0Copy(pObj) );
     if ( !Abc_NtkCheck( pNtkNew ) )
-        Abc_Print( 1, "Abc_NtkFromDar(): Network check has failed.\n" );
+    {
+        Abc_Print( 1, "Abc_NtkFromDar(): Network check has failed. Returning original network.\n" );
+        Abc_NtkDelete( pNtkNew );
+        pNtkNew = Abc_NtkDup( pNtkOld );
+    }
 
     // verify topological order
     if ( 0 )