ScriptRunner error in custom email listener

[Rich Scire]

When executing a custom email listener listener the below error is displayed in the logs and the email is never sent. When I run the preview function, the email is generated correctly. I attempted to put logging statements in the templates but the import statements generated errors. Ho can I go about debugging this?

Versions

JIRA 6.4.14

ScriptRunner 4.1.3.24

Email Template

Your request <A href="$baseurl/browse/$issue">$issue</A> has been submitted successfully. The aligned ESM <%

    String esmKeyString = issue.getCustomFieldValue(componentManager.getCustomFieldManager().getCustomFieldObjectByName("ESM's Name"));

    def (esmKey, value2) = esmKeyString.tokenize( '(' )

    def esmName = componentManager.getUserUtil().getUserByKey(esmKey).getDisplayName()

    out << esmName;

%> will be contacting you shortly.

Subject template

Issue $issue: A <%

    String companyName = issue.getCustomFieldValue(componentManager.getCustomFieldManager().getCustomFieldObjectByName("Company Name"));

    out << companyName;

%> request has been submitted successfully

Error

Time (on server): Fri Jan 27 2017 15:51:25 GMT-0500 (Eastern Standard Time)

The following log information was produced by this execution. Use statements like:log.info("...") to record logging information.

2017-01-27 14:51:25,773 ERROR [runner.AbstractScriptListener]: *************************************************************************************
2017-01-27 14:51:25,773 ERROR [runner.AbstractScriptListener]: Script function failed on event: com.atlassian.jira.event.issue.IssueEvent, script: com.onresolve.scriptrunner.canned.jira.workflow.postfunctions.SendCustomEmail
java.lang.NullPointerException: Cannot invoke method tokenize() on null object
	at com.onresolve.scriptrunner.canned.jira.workflow.postfunctions.SendCustomEmail.constructMail(SendCustomEmail.groovy:477)
	at com.onresolve.scriptrunner.canned.jira.workflow.postfunctions.SendCustomEmail$constructMail$0.callCurrent(Unknown Source)
	at com.onresolve.scriptrunner.canned.jira.workflow.postfunctions.SendCustomEmail.constructMailWithConditionResult(SendCustomEmail.groovy:457)
	at com.onresolve.scriptrunner.canned.jira.workflow.postfunctions.SendCustomEmail$constructMailWithConditionResult.callCurrent(Unknown Source)
	at com.onresolve.scriptrunner.canned.jira.workflow.postfunctions.SendCustomEmail.doScript(SendCustomEmail.groovy:553)

[JamieA]

You'd be better off putting this in the configuration so you can inject it in as a variable, and handle null as you wish.

https://scriptrunner.adaptavist.com/latest/jira/builtin-scripts.html#_additional_configuration_in_emails

[Vasiliy Zverev]

Main trouble is that variable "esmKeyString" is null. Since NullPointerExeption is raised.

It is null because there is no value for customfiled "ESM's Name"

There are two options to do

1. make this field mandatory
2. add try/catch block for NullPointerExeption