Rust

fix the null input and enhance tests #136

Job	Run time
cargo check	7m 23s
build with wasm-pack	2m 34s
cargo test (macos-aarch64)	11m 25s
cargo test (macos)	10m 21s
cargo test (win64)	43m 13s
Check cargo fmt	39s
Verify MSRV (Min Supported Rust Version)	7m 11s
Verify Vendored Code	51s
cargo test (amd64)	10m 15s
cargo test datafusion-cli (amd64)	3m 50s
cargo doc	4m 0s
Run sqllogictest with Postgres runner	3m 25s
verify benchmark results (amd64)	11m 44s
check Cargo.toml formatting	2m 42s
clippy	5m 31s
check configs.md is up-to-date	2m 42s
cargo test doc (amd64)	14m 55s
cargo examples (amd64)	13m 6s
cargo test pyarrow (amd64)	2m 58s
cargo test hash collisions (amd64)	14m 8s
	2h 52m 53s

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