Problem compiling world amd64

[filippo_at_sting ~]$ uname -a
FreeBSD sting 13.0-CURRENT FreeBSD 13.0-CURRENT #11 r365578: Thu Sep 10 19:38:51 CEST 2020     root_at_sting:/usr/obj/usr/src/amd64.amd64/sys/STING  amd64

I have the following error during buildworld:ed '1s/\/bin\//\/rescue\//' /usr/src/rescue/rescue/../../sbin/reboot/nextboot.sh > nextboot_FIXED
--- dhclient_FIXED ---
sed '1s/\/bin\//\/rescue\//' /usr/src/rescue/rescue/../../sbin/dhclient/dhclient-script > dhclient_FIXED
--- all_subdir_stand ---
===> stand (all)
--- all_subdir_stand/libsa ---
===> stand/libsa (all)
--- include/machine ---
include/machine -> /usr/src/sys/amd64/include
--- include/x86 ---
include/x86 -> /usr/src/sys/x86/include
--- beforedepend ---
mkdir -p xlocale arpa;  for i in a.out.h assert.h elf.h limits.h nlist.h setjmp.h stddef.h stdbool.h string.h strings.h time.h unistd.h uuid.h; do  ln -sf /usr/src/include/$i $i;  done;  ln -sf /usr/src/sys/amd64/include/stdarg.h stdarg.h;  ln -sf /usr/src/sys/sys/errno.h errno.h;  ln -sf /usr/src/sys/sys/stdint.h stdint.h;  ln -sf /usr/src/include/arpa/inet.h arpa/inet.h;  ln -sf /usr/src/include/arpa/tftp.h arpa/tftp.h;  for i in _time.h _strings.h _string.h; do  [ -f  xlocale/$i ] || cp /dev/null xlocale/$i;  done;  for i in ctype.h fcntl.h signal.h stdio.h stdlib.h; do  ln -sf /usr/src/stand/libsa/stand.h $i;  done
cp: /dev/null: Invalid argument
*** [beforedepend] Error code 1

make[4]: stopped in /usr/src/stand/libsa
--- all_subdir_secure ---
--- all_subdir_share ---
--- all_subdir_lib ---

The error is recurringFilippo