Jenkins Pipeline Failure Reason

I've come across older questions on this topic. Namely

• Get error reason in Jenkinsfile failure
• Get failure reason from Jenkins pipeline

But, by now, I'd expect the Jenkins Pipeline to have this functionality baked, rather than hacked, in.

When running a post script in a Jenkins Pipeline is there any way to find the build failure? e.g. Via an environmental variable, currentBuild, etc.

pipeline {
    agent none
    stages {
        stage("Validate") {
            parallel {
                stage("Ubuntu") {
                    agent {
                        label "UBUNTU"
                    }
                    steps {
                        sh "cause failure"
                    }
                }
            }
        }
    }
    post { 
        failure { 
            sendFailureMessage(`failure reason here`)
        }
        aborted { 
            sendFailureMessage(`failure reason here`)
        }
        unstable { 
            sendFailureMessage(`failure reason here`)
        }
    }
}