apt install failures with /compat/ubuntu

After following /compat/ubuntu advice in the FreeBSD wiki, I attempted 
installation of two things. Both failed in the same way.

The second example:

root_at_mowa219-gjp4-8570p:/# apt install htop
Reading package lists... Done
Building dependency tree
Reading state information... Done
htop is already the newest version (2.1.0-3).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up rsyslog (8.32.0-1ubuntu4) ...
The user `syslog' is already a member of `adm'.
Failed to fstat() file /var/spool/rsyslog: Invalid argument
Failed to fstat() file /var/log: Invalid argument
dpkg: error processing package rsyslog (--configure):
  installed rsyslog package post-installation script subprocess returned 
error exit status 1
Errors were encountered while processing:
  rsyslog
E: Sub-process /usr/bin/dpkg returned an error code (1)
root_at_mowa219-gjp4-8570p:/# exit
exit
root_at_mowa219-gjp4-8570p:~ # date ; uname -v
Wed Feb 24 18:41:54 GMT 2021
FreeBSD 14.0-CURRENT #87 main-5ac839029d: Mon Feb 22 04:02:26 GMT 2021 
root_at_mowa219-gjp4-8570p:/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG
root_at_mowa219-gjp4-8570p:~ # freebsd-version -kru
14.0-CURRENT
14.0-CURRENT
14.0-CURRENT
root_at_mowa219-gjp4-8570p:~ # cat /etc/fstab
# Device        Mountpoint              FStype 
Options                      Dump  Pass#
/dev/ada0p3.eli none                    swap 
sw,late                      0     0
# linprocfs     /compat/linux/proc      linprocfs 
rw                           0     0
# linsysfs      /compat/linux/sys       linsysfs 
rw                           0     0
# tmpfs         /compat/linux/dev/shm   tmpfs 
rw,mode=1777                 0     0
tmpfs           /tmp                    tmpfs 
rw,mode=01777                0     0
fdescfs         /dev/fd                 fdescfs 
rw                           0     0
proc            /proc                   procfs 
rw                           0     0
# <https://wiki.freebsd.org/LinuxJails>
devfs           /compat/ubuntu/dev      devfs 
rw,late                      0       0
tmpfs           /compat/ubuntu/dev/shm  tmpfs 
rw,late,size=1g,mode=1777    0       0
fdescfs         /compat/ubuntu/dev/fd   fdescfs 
rw,late,linrdlnk             0       0
linprocfs       /compat/ubuntu/proc     linprocfs 
rw,late                      0       0
linsysfs        /compat/ubuntu/sys      linsysfs 
rw,late                      0       0
/tmp            /compat/ubuntu/tmp      nullfs 
rw,late                      0       0
/home           /compat/ubuntu/home     nullfs 
rw,late                      0       0
root_at_mowa219-gjp4-8570p:~ # chroot /compat/ubuntu /bin/sh
# apt install htop
Reading package lists... Done
Building dependency tree
Reading state information... Done
htop is already the newest version (2.1.0-3).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up rsyslog (8.32.0-1ubuntu4) ...
The user `syslog' is already a member of `adm'.
Failed to fstat() file /var/spool/rsyslog: Invalid argument
Failed to fstat() file /var/log: Invalid argument
dpkg: error processing package rsyslog (--configure):
  installed rsyslog package post-installation script subprocess returned 
error exit status 1
Errors were encountered while processing:
  rsyslog
E: Sub-process /usr/bin/dpkg returned an error code (1)
# exit
root_at_mowa219-gjp4-8570p:~ #