New comment by darmon77 on void-packages repository

https://github.com/void-linux/void-packages/issues/30173#issuecomment-817455967

Comment:
The icecat profile in firejail is the firefox-common.profile 
I am using firejail on a musl system and I don't have the problem you mention.
try to reproduce the behavior you indicate in xorg and wayland 
also run firecfg and log out and then try to run icecat
`➜  ~ icecat
Reading profile /etc/firejail/icecat.profile
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 18707, child pid 18708
Warning: cannot find /var/run/utmp
Warning: An abstract unix socket for session D-BUS might still be available. Use --net or remove unix from --protocol set.
Warning: cleaning all supplementary groups
Warning: /sbin directory link was not blacklisted
Warning: /usr/sbin directory link was not blacklisted
Warning: cleaning all supplementary groups
Seccomp list in: !chroot, check list: @default-keep, prelist: unknown,
Child process initialized in 253.11 ms
JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 127: TypeError: cache is undefined
JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 127: TypeError: cache is undefined
JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 127: TypeError: cache is undefined
JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 127: TypeError: cache is undefined
JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 127: TypeError: cache is undefined

Parent is shutting down, bye...
`