Error: this.cells3(_x, i) is undefined Source

A sample is created for file but while integrated with some big applcn its throwing an error
When trying to copy data in clipboard
Error: this.cells3(_x, i) is undefined
Source File: localhost:8080/applcn/dhtmlx/dht … lection.js
Line: 89

Try to replace 3 with 2

this.cells2...