Hard to debug log

[plohan]

Current logging system is very unhelpful. For example, grader may throw Err(InvalidIO) with out even telling which file it were trying operate on.

[plohan]

Another real example:

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: NotPresent', interface/src/main.rs:102:43

[pongsaphol]

agree