How to use correctly cps notation in Jenkins pipeline - jenkins

Question

I am trying to write some code in Jenkins, but my knowledge is quite limited, I need to read some information (the commiter for that CL) from a xml file that Perforce generates(SCM) I then use that information I get, in another function to send an email in case the static analysis finds an error, the thing is I keep getting the expected to call WorkflowScript.sendEmailNewErrors but wound up catching readJSON Error, I have gone through the CPS documentation The output tells me but honestly it is still not clear to me what is wrong. My pipeline would be something like this:
import groovy.json.JsonSlurper
#NonCPS
def sendEmailNewErrors(){
def submitter = findItemInChangelog("changeUser")
def Emails = readJSON file: "D:/Emails.json"
def email = "test#email.com"
def msgList = []
def url = "http://localhost:8080/job/job1/1374/cppcheck/new/api/json"
def json = new JsonSlurper().parseText(new URL(url).text)
for (key in Emails.keySet()) {
if (submitter == key){
email = Emails.get(key)
}
}
json.issues.each{issue->
def msg = "New ERROR found in static analysis, TYPE OF ERROR ${issue.type}"+
", SEVERITY: ${issue.severity}, ERROR MESSAGE: ${issue.message}"+
", FILE ${issue.fileName} AT LINE: ${issue.lineStart}"
msgList.add(msg)
}
msgList.each{msg->
println msg
mail to: email,
subject: "New errors found in job1 build pipeline",
body: "$msg"
}
}
#NonCPS
def findItemInChangelog(item){
def result = "Build ran manually"
def found = false
def file = new XmlSlurper().parse("C:/Users/User/.jenkins/jobs/job1/builds/1374/changelog5966810591791724161.xml")
file.entry.each { entry ->
entry.changenumber.each { changenumber ->
changenumber.children().each { tag ->
if(tag.name() == item && found != true){
result = tag.text()
found = true
}
}
}
}
return result.toString()
}
pipeline {
agent any
stages {
stage("test"){
steps{
script{
sendEmailNewErrors()
}
}
}
}
}
I have tried without CPS notation but I understand if using .each method the notation has to be used. Anyone with more experience with this is able to help?