Bug/dimensionbyvalueissue (#2033)

* Fixed an issue where ExcelWorksheet.DimensionByValue returned the wrong address

* Small fix for RangeInfo when Worksheet is empty

* Fixed failing test

Author: JanKallman

src/EPPlus/Core/CellStore/CellStore.cs

@@ -1175,7 +1175,6 @@ public void Dispose()
 
         internal bool NextCell(ref int row, ref int col)
         {
-
             return NextCell(ref row, ref col, 0, 0, ExcelPackage.MaxRows, ExcelPackage.MaxColumns);
         }
         internal bool NextCell(ref int row, ref int col, int minRow, int minColPos, int maxRow, int maxColPos)
@@ -1543,6 +1542,11 @@ internal bool GetPrevCell(ref int row, ref int colPos, int startRow, int startCo
                             }
 
                             var c = colPos - 1;
+                            if (c < 0 && endColPos > colPos && row>1)
+                            {
+                                c = endColPos;
+                                row--;
+                            }
                             if (c >= startColPos)
                             {
                                 while (c != colPos)

src/EPPlus/FormulaParsing/Ranges/RangeInfo.cs

@@ -68,7 +68,7 @@ public RangeInfo(FormulaRangeAddress address)
         public RangeInfo(ExcelWorksheet ws, int fromRow, int fromCol, int toRow, int toCol, ParsingContext ctx, int extRef = -1)
         {
             var address = new ExcelAddressBase(fromRow, fromCol, toRow, toCol);
-            address._ws = ws.Name;
+            address._ws = ws?.Name;
             SetAddress(ws, address, ctx);
             _addresses[0].ExternalReferenceIx = extRef;
         }

src/EPPlusTest/Issues/WorksheetIssues.cs

@@ -840,5 +840,19 @@ public void s843()
 
             sheet.Cells["C3"].AddComment("Test"); // NullReferenceException 
         }
+        [TestMethod]
+        public void DimensionByValueIssue()
+        {
+            using (var p = OpenTemplatePackage("DimensionByValueError.xlsx"))
+            {
+                var ws = p.Workbook.Worksheets["Technical"];
+                var dv = ws.DimensionByValue;
+                Assert.AreEqual("C3", dv.Start.Address);
+                Assert.AreEqual("M60", dv.End.Address);
+                Assert.AreEqual("C3", ws.FirstValueCell.Address);
+                Assert.AreEqual("J60", ws.LastValueCell.Address);
+                SaveAndCleanup(p);
+            }
+        }
     }
 }