I am extremely new to Blueocean & getting below error when trying to open pipeline editor -

There was an error loading the pipeline from the Jenkinsfile in this repository. Correct the error by editing the Jenkinsfile using the declarative syntax then commit it back to the repository.

Cannot read property 'indexOf' of undefined

View full Jenkinsfile - 
https://stackoverflow.com/questions/46169459/jenkins-blueocean-plugin-pipeline-editor-unable-to-open-jenkinsfile

Blueocean plugin version - 1.2.2 .