Request.ifAuthenticatedInRole results in a null-reference error when the user is not authenticated.

[bkrug]

I am running into the same issue as aghouton: https://github.com/orgs/falcoframework/discussions/148

• Expected: When a user has a required role, Request.ifAuthenticatedInRole runs the supplied httpHandler
• Expected: When an authenticated user does not have a required role, Request.ifAuthenticatedInRole does not run the supplied httpHandler
• Not Expected: When a user is not authenticated, Request.ifAuthenticatedInRole throws an exception.

I have reproduced the issue here: https://github.com/bkrug/expose-falco-role-authorization-bug

On my local PC, I have cloned the Falco repo written the following test.
I have also written code to make the test pass.
I would be willing to push a branch and create a pull request, or to share my branch in any other way.

[<Fact>]
let ``Request.ifAuthenticatedInRole should block non-authenticated users`` () =
    let ctx = getHttpContextWriteable false

    let mutable visited = false

    let handle : HttpHandler = fun ctx ->
        visited <- true
        Response.ofEmpty ctx

    task {
        do! Request.ifAuthenticatedInRole AuthScheme ["admin2"] handle ctx
        visited |> should equal false
    }

[bkrug]

I've now created a fork and a pull request.
I would have done this a week ago, but I'm not used to open source work.