Fix the panic in `follows_from` #301

Job	Run time
cargo check	41s
warnings	47s
build tests (wasm32-unknown-unknown)	1m 4s
cargo check (feature combinations)	20s
cargo check (+MSRV -Zminimal-versions) (stable)	35s
cargo check (+MSRV -Zminimal-versions) (1.75.0)	30s
build tests (wasm32-wasip1)	1m 0s
cargo test (stable on ubuntu-latest)	54s
cargo fmt	10s
cargo test (nightly on ubuntu-latest)	1m 0s
cargo test (stable on windows-latest)	3m 55s
cargo test (stable on macos-latest)	1m 30s
cargo test (beta on ubuntu-latest)	1m 4s
all systems go!	3s
	13m 33s

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