fixed bug

Scripts/UI/Component/Series.cs

@@ -78,6 +78,7 @@ namespace XCharts
         /// <returns></returns>
         public Serie GetSerie(string name)
         {
+            if (string.IsNullOrEmpty(name)) return null;
             for (int i = 0; i < m_Series.Count; i++)
             {
                 if (name.Equals(m_Series[i].name))