wasm test failures do not contain error messages

[tmandry]

When our tests fail in bors on a wasm target, there is no error message except RuntimeError: unreachable (example). There is nothing to print the panic message to the console.

I think this could be fixed by adding console_error_panic_hook as dependency somehow, but I'm not quite sure how to do this.

Here's an example project that sets up this dependency to run with a test: async-fn-size. Thanks to @Mark-Simulacrum for figuring this out!

[oli-obk]

In #66321 (comment) it was suggested to try to

use std::panic::set_hook only during the tests to retrieve the panic message?