Formatting and error handling

src/main.rs

..._game-4705d3f68048a38e/bin-guessing_game-4705d3f68048a38e

...-4705d3f68048a38e/bin-guessing_game-4705d3f68048a38e.json

target/debug/deps/guessing_game-4705d3f68048a38e

target/debug/guessing_game

target/release/.cargo-lock

..._game-ff40b6649dac356e/bin-guessing_game-ff40b6649dac356e

...-ff40b6649dac356e/bin-guessing_game-ff40b6649dac356e.json

...e-ff40b6649dac356e/dep-bin-guessing_game-ff40b6649dac356e

...print/libc-2ef5206794533cd4/dep-lib-libc-2ef5206794533cd4

...ngerprint/libc-2ef5206794533cd4/lib-libc-2ef5206794533cd4

...rint/libc-2ef5206794533cd4/lib-libc-2ef5206794533cd4.json

...print/rand-74d8781095965d13/dep-lib-rand-74d8781095965d13

...ngerprint/rand-74d8781095965d13/lib-rand-74d8781095965d13

...rint/rand-74d8781095965d13/lib-rand-74d8781095965d13.json

target/release/deps/guessing_game-ff40b6649dac356e

target/release/deps/liblibc-2ef5206794533cd4.rlib

target/release/deps/librand-74d8781095965d13.rlib

target/release/guessing_game

target/release/guessing_game.d