What's the best way to improve error message and code position in thread?

#1

To understand error handling in std::thread and tokio_threadpool, I modified the example
https://docs.rs/tokio-threadpool/0.1.11/tokio_threadpool/fn.blocking.html#examples
and make an error happen.

Then I noticed the error message is like below:

thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: RecvError', src/libcore/result.rs:1009:5

I think the code position is not helpful since it is the position in the standard library, not my application code.

Then I use map_err and got improved error messages.

comparison with for witouht map_err for std::thread:

comparison with for witouht map_err for tokio_threadpool:

Is there a better way to get the correct code position in error messages for code in thread?

My rustc version is:

$ rustup show
Default host: x86_64-unknown-linux-gnu

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu

active toolchain
----------------

stable-x86_64-unknown-linux-gnu (default)
rustc 1.32.0 (9fda7c223 2019-01-16)

Thanks!