Behaviour failed to load after the field required error prompt when submitting a form in "secure/CreateIssueDetails.jspa"

Steps to Reproduce

1. Create a new behaviour mapped to a project
2. Configure a server-side script on a single select list:

   import static com.atlassian.jira.issue.IssueFieldConstants.*
   
   def selectList = getFieldById(fieldChanged)
   def selectListValue = selectList.value
       
   def priority = getFieldById(PRIORITY)
   def summary = getFieldById(SUMMARY)
   
   log.warn"selectListValue : ${selectListValue} "
   
   if(selectListValue == "A"){
       priority.setFormValue("High")
       priority.setReadOnly(true)
       summary.setFormValue("This is an important creation ticket")
   } else {
       priority.setFormValue("Low")
       priority.setReadOnly(true)
       summary.setFormValue("This is an important creation ticket")
   }
   

3. Open create screen in a new tab or "secure/CreateIssueDetails.jspa"
4. Have at least one mandatory field
5. Click "Create" without completing one of the mandatory fields

Steps to Reproduce 2

There are other ways to reproduce a similar bug:

1. Create a behaviour mapped to a project
2. Configure a server-side script on a single select list:

   getFieldByName("Select list").setFormValue('A')
   

3. Set the field as Readonly.
4. Open create screen in a new tab or "secure/CreateIssueDetails.jspa"
5. Have at least one mandatory field or do not fill up Summary field.
6. Click "Create" button twice.
7. Result: The select list field will be set to Readonly, but the setFormValue does not run.

Recording of Behaviour: SRJIRA-5686_Step_to_Reproduced_2.mp4

Expected Behaviour

Behaviours able to run again after the error is thrown

Actual Behaviour

Behaviours failed to run again after the error is thrown

Additional Info

A short video on the step to reproduce