TwingFunction just doesn't seem to work

[Bilge]

When adding the most trivial custom function such as the following:

twing.addFunction(new TwingFunction('is_granted', _ => true));

the browser error as follows:

TwingErrorRuntime: An exception has been thrown during the rendering of a template ("callable.apply(...).catch is not a function") in "C:/templates/component/tier.twig".
traceableCallable callable-wrapper.js:44
doDisplay tier.twig:22
displayWithErrorHandling template.js:319
display template.js:316
promise callbackdisplay template.js:316
render template.js:337
exports tier.twig:50
promise callback../templates/component/tier.twig/module.exports tier.twig:50

Indeed, I'm not sure why it expects there would be a property called catch attached to my anonymous function?

twing/src/lib/callable-wrapper.ts

Line 79 in 56e186b

return (callable.apply(null, arguments) as Promise<T>).catch((e: TwingError) => {

[Bilge]

It seems I need to use Promise.resolve(true) for reasons that remain unclear to me.