Cannot run Firefox without libcanberra-gtk3-module

[David F.]

In https://askubuntu.com/questions/775461/packages-to-run-firefox-window-on-a-server the question author reports that it's impossible to start Firefox through X forwarding without installing libcanberra-gtk3-module manually (see the accepted answer https://askubuntu.com/a/781210/175814). This package isn't typically installed on systems without a desktop environment.

Here's what they did:

 1. Open an SSH connection with X forwarding (-X or -Y).

 2. Run "firefox -no-remote".

Expected behaviour:
A Firefox window is opened in the client session.

Actual behaviour:
No window is opened and the terminal shows the error:

    Gtk-Message: Failed to load module "canberra-gtk-module"

I see that libcanberra0 is among the Recommended section of the firefox package but it seems to be of no use there if Firefox cannot run without it and it's unclear whether that package alone is enough. Should we add a mandatory dependency on libcanberra-gtk3-module?