Fixes issue #2228

Author: JanKallman

src/EPPlus/Core/ChangableDictionary.cs

@@ -61,20 +61,21 @@ internal virtual void InsertAndShift(int fromPosition, int add)
         {
             var pos = Array.BinarySearch(_index[0], 0, _count, fromPosition);
 
-            if (pos + 1 >= _index[0].Length - 1)
+            if (pos < 0)
             {
-                Array.Resize(ref _index[0], _index[0].Length << 1);
-                Array.Resize(ref _index[1], _index[1].Length << 1);
+                pos = ~pos;
             }
 
-            if (pos<0)
+            if (pos + 1 >= _index[0].Length - 1)
             {
-                pos = ~pos;
+                Array.Resize(ref _index[0], _index[0].Length << 1);
+                Array.Resize(ref _index[1], _index[1].Length << 1);
             }
 
             Array.Copy(_index[0], pos, _index[0], pos + 1, _count - pos);
             Array.Copy(_index[1], pos, _index[1], pos + 1, _count - pos);
 
+
             _count++;
             for (int i=pos;i<Count;i++)
             {

src/EPPlusTest/Issues/CellStoreIssues.cs

@@ -0,0 +1,52 @@
+/*******************************************************************************
+ * You may amend and distribute as you like, but don't remove this header!
+ *
+ * Required Notice: Copyright (C) EPPlus Software AB. 
+ * https://epplussoftware.com
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
+ * See the GNU Lesser General Public License for more details.
+ *
+ * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
+ * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
+ *
+ * All code and executables are provided "" as is "" with no warranty either express or implied. 
+ * The author accepts no liability for any damage or loss of business that this product may cause.
+ *
+ * Code change notes:
+ * 
+  Date               Author                       Change
+ *******************************************************************************
+  01/27/2020         EPPlus Software AB       Initial release EPPlus 5
+ *******************************************************************************/using Microsoft.VisualStudio.TestTools.UnitTesting;
+using OfficeOpenXml;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace EPPlusTest.Issues
+{
+    [TestClass]
+    public class CellStoreIssues
+    {
+        [TestMethod]
+        public void Issue2228()
+        {
+            using var pck = new ExcelPackage();
+            var worksheet = pck.Workbook.Worksheets.Add("Sheet1");
+            for (int i = 1; i < 10; i++)
+            {
+                worksheet.InsertColumn(i, 1);
+            }
+        }
+    }
+}