fix for processing#7259

Check for negative indices and skip shape drawing if index is negative

Author: digitaldina

src/accessibility/gridOutput.js

@@ -66,7 +66,9 @@ function _gridMap(idT, ingredients) {
       // Check if shape is in canvas, skip if not
       if(
         ingredients[x][y].loc.locY < cells.length &&
-        ingredients[x][y].loc.locX < cells[ingredients[x][y].loc.locY].length
+        ingredients[x][y].loc.locY >= 0  && ingredients[x][y].loc.locX >= 0
+        ingredients[x][y].loc.locX < cells[ingredients[x][y].loc.locY].length 
+        
       ){
         //if empty cell of location of shape is undefined
         if (!cells[ingredients[x][y].loc.locY][ingredients[x][y].loc.locX]) {