fix misplaced comment in error handling example #5826

Job	Run time
check	40s
check-docs	50s
dependencies-are-sorted	6s
cargo-hack	2m 41s
cargo-public-api-crates (axum-extra)	27s
cargo-deny check (advisories)	28s
cargo-public-api-crates (axum)	36s
cargo-deny check (bans licenses sources)	28s
Spell Check with Typos	8s
cargo-public-api-crates (axum-core)	18s
cargo-public-api-crates (axum-macros)	18s
test-nightly	1m 1s
test-versions (beta)	1m 8s
test-versions (stable)	1m 23s
test-docs	1m 15s
wasm32-unknown-unknown	26s
armv5te-unknown-linux-musleabi	34s
test-msrv	2m 4s
	14m 51s

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