Fix `clippy::unnecessary_map_or` lint #750

Job	Run time
cargo clippy (android) (armv7-linux-androideabi)	1m 4s
cargo check (msrv) (android) (armv7-linux-androideabi)	21s
cargo clippy (android) (aarch64-linux-android)	1m 43s
cargo check (msrv) (windows-latest)	54s
cargo check (msrv) (android) (aarch64-linux-android)	48s
cargo clippy (windows-latest)	1m 46s
cargo check (msrv) (macos-latest)	29s
cargo clippy (macos-latest)	56s
cargo check (msrv) (android) (x86_64-linux-android)	50s
cargo clippy (ubuntu-latest)	1m 3s
cargo clippy (android) (x86_64-linux-android)	1m 43s
cargo check (msrv) (ubuntu-latest)	31s
cargo doc (windows-latest)	2m 52s
formatting	25s
cargo doc (macos-latest)	58s
cargo test (windows-latest)	1m 49s
cargo doc (ubuntu-latest)	1m 19s
cargo test (macos-latest)	34s
typos	5s
cargo test (ubuntu-latest)	38s
	20m 48s

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