Extending Array prototype creates error

Whenever I try to extend the Array prototype the following error repeatedly occurs:

TypeError: Cannot call method 'getProgram' of undefined
    at XML3D.extend.renderObjectsToActiveBuffer (http://localhost:8080/xml3d/js/xml3d-4.5.1.js:23663:46)
    at XML3D.extend.renderScene (http://localhost:8080/xml3d/js/xml3d-4.5.1.js:23622:26)
    at XML3D.extend.renderToCanvas (http://localhost:8080/xml3d/js/xml3d-4.5.1.js:23145:39)
    at CanvasHandler.draw (http://localhost:8080/xml3d/js/xml3d-4.5.1.js:19319:39)
    at tick (http://localhost:8080/xml3d/js/xml3d-4.5.1.js:19220:22) 

[lachsen]

In one point of the code we used an array when we wanted to use an object.
I fixed this now, so this issue should be solved.