Access to the choices global variable in installation-check script?

Is it possible to access the choices global variable in an installation-check script when the package doesn't have choices that the end-user can interact with?

I'm referring to this:

https://developer.apple.com/documentation/installer_js/choice

It seems to imply that you can access the choices global variable, but any attempt to do so fails. For example, take the following:

Code Block 
<?xml version="1.0" encoding="utf-8"?>
<installer-gui-script minSpecVersion="2">
    <title>My Meta Package</title>
    <pkg-ref id="com.md4.myapp"/>
    <options customize="never" require-scripts="false" rootVolumeOnly="true" />
    <choices-outline>
        <line choice="default">
            <line choice="myapp"/>
        </line>
    </choices-outline>
    <choice id="default"/>
    <choice id="myapp" visible="false" title="this is a test" description="testing one" start_selected="true">
        <pkg-ref id="com.md4.myapp"/>
    </choice>
    <pkg-ref id="com.md4.myapp" version="1" onConclusion="none">mypackage.pkg</pkg-ref>
    <installation-check script="version_check()" />
    <script>
<![CDATA[
function version_check()
{
    title = choices.['myapp'].title;
    system.log("Performing custom installation check against version " + system.version.ProductVersion);
    system.log("Title " + title);
    return true;
}
]]>
    </script>
</installer-gui-script>

This results in the following:

Sep 8 15:32:56 THY-01-0236-LT Installer[85217]: IFJS: *** exception: SyntaxError: Unexpected token '['. Expected a property name after '.'.

Is it possible to access the choices global variable in this manner? If so, what is the correct way/syntax to do it?

Thanks in advance!