Fix exception thrown when restoring data in specific circumstances.

Author: anmcgrath

src/BlazorDatasheet.DataStructures/Intervals/MergeableIntervalStore.cs

@@ -435,7 +435,15 @@ public virtual void Restore(MergeableIntervalStoreRestoreData<T> restoreData)
     {
         foreach (var shift in restoreData.Shifts)
         {
-            foreach (var interval in GetIntervals(shift.Index, int.MaxValue))
+            var intervals = GetIntervals(shift.Index, int.MaxValue);
+            IEnumerable<OrderedInterval<T>> intervalsOrdered;
+            
+            if (shift.Amount > 0)
+                intervalsOrdered = intervals.OrderBy(i => i.Start);
+            else
+                intervalsOrdered = intervals.OrderByDescending(i => i.Start);
+
+            foreach (var interval in intervalsOrdered)
             {
                 _intervals.Remove(interval.Start);
                 interval.Shift(-shift.Amount);

test/BlazorDatasheet.Test/Commands/RemoveRowColCommandTests.cs

@@ -184,4 +184,17 @@ public void Remove_Col_Intersects_With_Edge_Of_region_Restores_On_Undo()
         cmd.Undo(sheet);
         sheet.GetFormat(0, 1)?.HorizontalTextAlign.Should().Be(TextAlign.Center);
     }
+
+    [Test]
+    public void Remove_Col_Before_Format_And_Undo_Does_Not_Throw_Error()
+    {
+        Assert.DoesNotThrow(() =>
+        {
+            var sheet = new Sheet(10, 10);
+            sheet.Range("E:E").Format = new CellFormat() { HorizontalTextAlign = TextAlign.Center };
+            sheet.Range("D:D").Format = new CellFormat() { NumberFormat = "C1", FontWeight = "bold" };
+            sheet.Columns.RemoveAt(2);
+            sheet.Commands.Undo();
+        });
+    }
 }