accessing keyStack

[BobCarver]

I would like to use the verify method on the key stack. I have assigned keys to they app so I know the key stack exists; however, in my middleware the compiler complains when I try to access the verify method.
i.e. ctx.app.keys.verify(foo)
I think it is because the compiler thinks that keys is of type: keyStack | keys[] | undefined.

Here is the code I am using:

type Resource = 'job' | 'user'

type qs = Record<Resource, {
'GET'?: string,
'PUT'?: string,
'POST'?: string,
'DELETE'?: string
}>
const queryStrings:qs = {
'job':{ 'GET': 'query 1...' },
'user': { 'GET': 'query 2...'
}
}

async function restAPI(ctx: RouterContext<'/:resource(job|user)/:id(\d*)'>) {
const token = ctx.request.headers.get("Authorize")?.replace(/bearer\s*/, '');
ctx.assert(token, 400, 'No bearer token');

const claims = await ctx.app.keys.verify(token); //<-- current problem
const queryString = queryStrings[ctx.params.resource][ctx.request.method] //<-- next problem
ctx.assert(queryString, 405, method not allowed for ${ctx.params.resource});
/* finally do the query and return the result */

...
const router = new Router()
router.all('/:resource/:id(\d*)', restAPI)
const app = new Application();
app.keys = ['secret1','secret 2'] // <- should trigger the creation of the KeyStack

app.use(router.routes(), router.allowedMethods());

await app.listen({ port:8080 });

I am pretty sure I need to extend the RouterContex to indicate that keys will always be a KeyStack but I don't know how. (Just started using typescript.)

The next problem I think I will have is ctx.params.resource will have a string - but I really want it to be a Resource