Fix breakage caused by AsRef removal and error cleanup #977

Job	Run time
Clippy	1m 0s
Build docs	1m 19s
Rustfmt	8s
Test (MSRV)	1m 28s
Test (stable)	2m 10s
Test (beta)	2m 1s
Test (nightly)	2m 6s
Test (macOS)	3m 18s
Test (Windows)	4m 54s
Test (no features)	1m 10s
Test (all features - simdjson, cargo test --all-features --lib --tests --examples)	1m 13s
Test (native TLS, cargo test --all-features --features serenity/native_tls_backend --lib --tests ...	1m 15s
	22m 2s

Provide feedback