fix: crash when holding shift + arrow down then arrow up in last row of data grid

Closes #1451

Author: ansgarbecker

source/main.pas

@@ -10921,9 +10921,9 @@ procedure TMainForm.AnyGridKeyDown(Sender: TObject; var Key: Word; Shift: TShift
         Key := 0;
       end;
     end;
-    VK_RETURN: if Assigned(g.FocusedNode) then g.EditNode(g.FocusedNode, g.FocusedColumn);
-    VK_DOWN: if g.FocusedNode = g.GetLast then actDataInsertExecute(actDataInsert);
-    VK_NEXT: if (g = DataGrid) and (g.FocusedNode = g.GetLast) then actDataShowNext.Execute;
+    VK_RETURN: if Assigned(g.FocusedNode) and (Shift=[]) then g.EditNode(g.FocusedNode, g.FocusedColumn);
+    VK_DOWN: if (g.FocusedNode = g.GetLast) and (Shift=[]) then actDataInsertExecute(actDataInsert);
+    VK_NEXT: if (g = DataGrid) and (g.FocusedNode = g.GetLast) and (Shift=[]) then actDataShowNext.Execute;
   end;
 end;