New issue by ben-cooper on void-packages repository

https://github.com/void-linux/void-packages/issues/31837

Description:
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### System

* xuname:  
  Void 5.12.14_1 x86_64-musl AuthenticAMD notuptodate rFFFFF
* package:  
  firejail-0.9.66_1

### Expected behavior

Running `firejail firefox` or `firejail mpv` should launch these programs within firejail.

### Actual behavior

Running `firejail firefox` returns:

```
Reading profile /etc/firejail/firefox.profile
Reading profile /etc/firejail/whitelist-usr-share-common.inc
Reading profile /etc/firejail/firefox-common.profile
Reading profile /etc/firejail/disable-common.inc
Reading profile /etc/firejail/disable-devel.inc
Reading profile /etc/firejail/disable-exec.inc
Reading profile /etc/firejail/disable-interpreters.inc
Reading profile /etc/firejail/disable-programs.inc
Reading profile /etc/firejail/whitelist-common.inc
Reading profile /etc/firejail/whitelist-runuser-common.inc
Reading profile /etc/firejail/whitelist-var-common.inc
Seccomp list in: !chroot, check list: @default-keep, prelist: unknown,
Parent pid 19549, child pid 19552
Warning: cannot find /dev/null/utmp
Warning: An abstract unix socket for session D-BUS might still be available. Use --net or remove unix from --protocol set.
Error mounting tmpfs: fs.c:499 fs_tmpfs: Invalid argument
Error: proc 19549 cannot sync with peer: unexpected EOF
Peer 19552 unexpectedly exited with status 1
```

### Steps to reproduce the behavior

1. Run `firejail firefox` in the terminal.