Invalid hostname causes a crash

[Alex Band]

I entered dns9.quad9.org instead of dns9.quad9.net and caused dnsi to panic.

# dnsi query --tls --server dns9.quad9.org nlnetlabs.nl --format friendly
thread 'main' panicked at src/client.rs:84:9:
internal error: entered unreachable code
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace