mullvad-cli sometimes panics if not printing to stdout?

[rivke41levp656]

Is it a bug?

• I know this is an issue with the app, and contacting Mullvad support is not relevant.

I have checked if others have reported this already

• I have checked the issue tracker to see if others have reported similar issues.

Current Behavior

If the output of mullvad-cli is not printed to stdout, it sometimes panics.

Expected Behavior

It should not panic.

Steps to Reproduce

With mullvad-cli version 2025.4, and Rust version 1.84.1-1 on Arch Linux, capture the output of mullvad-cli, as in the following script:

#!/bin/bash

# Error occurs in ~15% of cases?
status="$(mullvad status | head -n1)"

# Errors ~1%?
read -r status < <(mullvad status)

# Errors ~100%.
status="$(mullvad status | echo)"

and it will sometimes print:

thread 'main' panicked at std/src/io/stdio.rs:1123:9:
failed printing to stdout: Broken pipe (os error 32)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Similar issue from another rust application: typst/typst#5439

I first noticed this after upgrading to mullvad version 2024.6 with Rust ver 1.82.0.

Failure Logs

Operating system version

No response

Mullvad VPN app version

No response

Additional Information

No response

[faern]

I can reproduce! Thank you for reporting this. We should handle stdout being closed in a better way.