[escher] TableView::cellAtLocation should return nullptr if the cell is

invisible and therefore no view displays it.

Fix bug: add 4 functions, in the values table one cell is wrong as soon
as you edit an x value

apps/code/console_controller.cpp

@@ -223,7 +223,9 @@ void ConsoleController::tableViewDidChangeSelection(SelectableTableView * t, int
     if (previousSelectedCellY > -1 && previousSelectedCellY < m_consoleStore.numberOfLines()) {
       // Reset the scroll of the previous cell
       ConsoleLineCell * previousCell = (ConsoleLineCell *)(t->cellAtLocation(previousSelectedCellX, previousSelectedCellY));
-      previousCell->reloadCell();
+      if (previousCell) {
+        previousCell->reloadCell();
+      }
     }
     ConsoleLineCell * selectedCell = (ConsoleLineCell *)(t->selectedCell());
     selectedCell->reloadCell();