Like mentioned in http://jenkins-ci.361315.n4.nabble.com/Email-Ext-and-Pipeline-Model-Definition-How-to-send-email-notifications-Culprits-and-Developers-as-r-td4853716.html#a4853724

Pipeline failure message when using 'emailext' step outside a 'node' step:

org.jenkinsci.plugins.workflow.steps.MissingContextVariableException: Required context class hudson.FilePath is missing

Of course, danielbeck's comment "How else are you going to attach files?" makes sense.

However, in my case I am not attaching any files and I am still using the Pipeline Script approach; seemingly in the Declarative Pipeline approach using a post build step to notify via 'emailext' step this is not an issue anymore?

Thus, (hoping this is not difficult and/or a lot of effort for you) can you please change it to not require a wrapping into a 'node' step, when there is no usage of attaching files? And if and only if files are being attached, require the node/workspace context?