[Bug]: Compiler crash when using xml:map with an xml union type

[poorna2152]

Description

Consider the following code,

public function main() {
    xml<xml:Element>|xml<xml:Comment> x1 = xml `<a><b><c><e>foo</e></c></b><d><g>bar</g></d></a>`;
    xml x2 = <xml> x1;
    _ = xml:map(xml:elements(x2), v => xml:getChildren(v));
}

When run this program crashes with the following log,

[2024-05-17 15:01:15,937] SEVERE {b7a.log.crash} - _1 
java.lang.NoSuchFieldError: _1
        at poorna.xmlns_def.0.main.main(main.bal:183)
        at poorna.xmlns_def.0.$_init.$moduleExecute(xmlns_def)
        at poorna.xmlns_def.0.$_init.$lambda$$moduleExecute$(xmlns_def)
        at io.ballerina.runtime.internal.scheduling.SchedulerItem.execute(SchedulerItem.java:54)
        at io.ballerina.runtime.internal.scheduling.Scheduler.run(Scheduler.java:320)
        at io.ballerina.runtime.internal.scheduling.Scheduler.runSafely(Scheduler.java:287)
        at java.base/java.lang.Thread.run(Thread.java:833)

Steps to Reproduce

No response

Affected Version(s)

2201.9.0

OS, DB, other environment details and versions

No response

Related area

-> Runtime

Related issue(s) (optional)

No response

Suggested label(s) (optional)

No response

Suggested assignee(s) (optional)

No response

[Thushara-Piyasekara]

Following is a simplified version of the code snippet which produces the same error,

public function main() {
    xml:Element|xml:Text x1 = xml `<a></a>`;
    _ = xml:map(xml:elements(<xml>x1), v => xml:getChildren(v));
}

[github-actions]

This issue is NOT closed with a proper Reason/ label. Make sure to add proper reason label before closing. Please add or leave a comment with the proper reason label now.

      - Reason/EngineeringMistake - The issue occurred due to a mistake made in the past.
      - Reason/Regression - The issue has introduced a regression.
      - Reason/MultipleComponentInteraction - Issue occured due to interactions in multiple components.
      - Reason/Complex - Issue occurred due to complex scenario.
      - Reason/Invalid - Issue is invalid.
      - Reason/Other - None of the above cases.

[poorna2152]

ballerina-platform/ballerina-release#2699