System.InvalidOperationExceptionWhen called from 'VisitMemberInit', rewriting a node of type 'System.Linq.Expressions.NewExpression' must return a non-null value of the same type. Alternatively, override 'VisitMemberInit' and change it to not visit children of this type. 

protected override Expression VisitMemberInit(MemberInitExpression node)
 {
       if (node.NewExpression.NodeType == ExpressionType.New) 
            return node;
        return base.VisitMemberInit(node);
 }