Function findSubEl

spec/regression-spec.ts:10–12

(id: string, index = 0)

    return grid.engine.nodes.find(n => n.id === id)!.el!;
  };
  let findSubEl = function(id: string, index = 0): GridItemHTMLElement {
    return grid.engine.nodes[index].subGrid?.engine.nodes.find(n => n.id === id)!.el!;
  };


  // empty grid