Code referring to sforce.opencti.* not working

[varun77sports]

Any code that has a reference of sforce.opencti.* is failing but if we comment it then it is works. when I digged a bit deeper then I can see error is coming from opencti.js code

"parent.postMessage(params, config.sfdcIframeOrigin);"

few more details

1. have whitelisted the URL
2. added to CSP as well