access denied

What's the best way to get some more information why this isn't working?
I assume this is because there is no way to obtain an acme cert?
Or would it fall back to self-signed certs?

```
use tide_acme::{AcmeConfig, TideRustlsExt};

#[async_std::main]
async fn main() -> tide::Result<()> {
let mut app = tide::new();
app.at("/").get(|_| async { Ok("Hello TLS") });

// app.listen("127.0.0.1:8080").await?;

app.listen(tide_rustls::TlsListener::build().addrs("127.0.0.1:4443").acme(
AcmeConfig::new()
.domains(vec!["domain.example".to_string()])
.contact_email("admin@example.org")
.cache_dir("/Users/foo/tide-acme-cache-dir"),
)
).await?;

Ok(())
}
```

```
$ curl -k https://localhost:4443
curl: (35) error:14004419:SSL routines:CONNECT_CR_SRVR_HELLO:tlsv1 alert access denied
```

Start with the TideRustlsExt and AcmeConfig setup shown in the issue, then reproduce the TLS listener with curl against localhost:4443. Investigate the access-denied alert and determine whether the configured ACME domain and cache directory permit certificate issuance; done means the failure cause and expected certificate fallback behavior are documented or corrected.

Written by the indexing model from the issue text.