docs: @Override
      public Object get(int index, Scriptable start)
      {
          if (externalData != null) {
              if (index < externalData.getArrayLength()) {
                  return externalData.getArrayElement(index);
              }
              return Scriptable.NOT_FOUND;
          }
  
          Slot slot = slotMap.query(null, index);
          if (slot == null) {
              return Scriptable.NOT_FOUND;
          }
          return slot.getValue(start);
      }