Unable to get property 'getDocumentPoint' of undefined or null reference

Hi I am facing issue mentioned in image only in Internet explorer Browser, But working fine in Google chrome.

As i’m getting Correct JSON Values in Both browser but in Internet Explorer it is pointing to Null Reference.
Can you please help me out.

Thanks in advance.

That’s in an override of a Link method, isn’t it?

Well, if the Link happens not to be connected to a node/port, then Link.toPort will be null, so you need to handle that case in your code. You probably need to handle Link.fromPort being null too.