Function in extends block results in javascript SyntaxError

The following piece of code is declared at the top of a twig file {% extends config("package_info") == "Page" ? "layout.html" : "modal.twig" %}

When the module gets loaded Twing produces the following error:

SyntaxError: missing ) after argument list
    at new Function (<anonymous>)
    at TwingEnvironmentNode.getTemplatesModule (/usr/src/app/node_modules/twing/dist/cjs/lib/environment.js:491:24)
    at /usr/src/app/node_modules/twing/dist/cjs/lib/environment.js:328:76
    at processTicksAndRejections (node:internal/process/task_queues:95:5)

This is the declaration of the config function:

const loader = new TwingLoaderArray(content)
const env = new TwingEnvironment(loader, {
    cache: false
})
env.addFunction(new TwingFunction(
    'url',
    (key) => Promise.resolve(vars[key]),
    [{name: 'key', defaultValue: ''}]
))

I have tried to resolve this myself but have hit a wall, it seems to be just the fault of Twing from my testing. When replacing the ternary operator with just one of the layout file names the template does render perfectly.