$ LOG_LEVEL=$(cat /dev/random | head -1) cargo script xxx.rs
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: NotUnicode("\xe1n\x99;\xa2\u{f}\xf6\x8e\u{13}b\'\xdb\u{12}JB\u{16}\u{7f}V~M\xbbaD\xaf6\'\u{1a}BL\xa6\xa0&>\x91xy\x9b\u{6}\xcbor\u{1e}Qg>\xd3\xc7j&\xb8\xdcn\xa4L\u{7}\xdf]\xef")

'LOG_LEVEL' not UTF-8 compatible!', src/libcore/result.rs:906:4
note: Run with `RUST_BACKTRACE=1` for a backtrace.