desktop-environment-toggle-mute doesn't work when current buffer is a remote file

[Divan Santana]

Hi

When you are editing say a remote file over tramp and call desktop-environment-toggle-mute function, one gets an error like so:

/bin/sh: amixer: command not found

Switching to a non-tramp buffer and calling the function again works around the issue.

[Damien Cassou]

I completely agree with you. Would you like to send a PR?