Debugging Powershell Sequential / Parallel Workflows and Error Reporting in Jenkinsfile

Jenkinsfile.groovy

def powershell_workflow(String mode, String... scripts) {
    powershell """
        echo "starting workflow in $mode mode"
        workflow runWorkflow {
            $mode {
                ${scripts.collect { script ->
                    "InlineScript { ${script} *>&1 | tee -filepath ${script.replace(' ','_')}.log; if(\$LastExitCode -ne 0) { Throw \"ERROR: \'$script\' failed with exit code \$LastExitCode \" } } -ErrorAction Continue"
                }.join('\n') }
            }
        }
        runWorkflow
        echo "done with workflow in $mode mode"
    """
}

node('Windows') {
    stage('create ps1 scripts') {
        //powershell "echo 'cmd /c \"exit 42\"; cmd /c \"exit 0\";' > shouldfailtoobutwont.ps1"
        powershell "echo 'sleep 1; echo failtoo.ps1; cmd /c \"exit 42\"' > failtoo.ps1"
        powershell "echo 'sleep 3; echo oktoo.ps1; cmd /c \"exit 0\"' > oktoo.ps1"
        powershell "echo 'sleep 1; echo fail.ps1; sleep 1; exit 8' > fail.ps1"
        powershell "echo 'sleep 6; echo ok.ps1; exit 0' > ok.ps1"
        powershell "echo 'sleep 2; echo okwithstderr.ps1; write-error doh; exit 0' > okwithstderr.ps1"
    }
    stage('test sequential') {
        powershell_workflow('sequence',
            "echo exit0; exit 0",
            //"C:/jenkins/workspace/xxx/fail.ps1",
            "C:/jenkins/workspace/xxx/ok.ps1",
            "C:/jenkins/workspace/xxx/oktoo.ps1",
            "C:/jenkins/workspace/xxx/okwithstderr.ps1"
        )
    }
    stage('test parallel') {
        powershell_workflow('parallel',
            "echo exit0; exit 0",
            //"C:/jenkins/workspace/xxx/fail.ps1",
            "C:/jenkins/workspace/xxx/ok.ps1",
            "C:/jenkins/workspace/xxx/oktoo.ps1",
            "C:/jenkins/workspace/xxx/okwithstderr.ps1"
        )
    }
}