Nominating fs-err.
When you use std::fs, you may get very unhelpful errors like
The system cannot find the file specified. (os error 2)
that don't show the path of the file on which the error occured.
fs-err wraps the functions in std::fs and adds the path information to the error while staying compatible with std::io::Error.
Saved me the pain of adding the error context myself everywhere.