module/zfs/vdev.c:6298:49: error: argument 1 is null but the corresponding size argument 3 value is 8192 [-Werror=nonnull]

[bocchi810]

System information

Type	Version/Name
Distribution Name	Debian
Distribution Version	Sid
Kernel Version	6.15.4
Architecture	x86_64
OpenZFS Version	6af8db6

Describe the problem you're observing

The compiler reports a null pointer error

Describe how to reproduce the problem

./configure \
  --prefix=/usr \
  --sysconfdir=/etc \
  --sbindir=/usr/sbin \
  --libdir=/usr/lib \
  --libexecdir=/usr/lib/zfs \
  --with-config=user \
  --enable-systemd \
  --enable-sysvinit \
  --enable-pam \
  --enable-pyzfs \
  --enable-debug \
  --enable-debuginfo \
  --enable-debug-kmem \
  --enable-debug-kmem-tracking \
  --enable-ubsan \
  --enable-asan \
  --enable-shared \
  --enable-static \
  --enable-fast-install \
  --enable-dependency-tracking \
  --enable-linux-experimental \
  --enable-code-coverage \
  --with-python=3 \
  --with-python-sys-prefix \
  --with-tirpc \
  --with-libunwind \
  --with-udevdir=/usr/lib/udev \
  --with-systemdunitdir=/usr/lib/systemd/system \
  --with-systemdpresetdir=/usr/lib/systemd/system-preset \
  --with-systemdmodulesloaddir=/usr/lib/modules-load.d \
  --with-systemdgeneratordir=/usr/lib/systemd/system-generators \
  --with-mounthelperdir=/sbin \
  --with-dracutdir=/usr/lib/dracut/modules.d \
  --with-zfsexecdir=/usr/libexec/zfs \
  --with-vendor=generic \
  --with-spec=generic
make -j12

Include any warning/errors/backtraces from the system logs

 CC       module/zfs/libzpool_la-vdev_rebuild.lo
module/zfs/vdev.c: In function 'vdev_prop_get':
module/zfs/vdev.c:6298:49: error: argument 1 is null but the corresponding size argument 3 value is 8192 [-Werror=nonnull]
 6298 |                                                 strlcat(strval, ",",
      |                                                 ^~~~~~~~~~~~~~~~~~~~
 6299 |                                                     ZAP_MAXVALUELEN);
      |                                                     ~~~~~~~~~~~~~~~~
In file included from ./lib/libspl/include/string.h:31,
                 from ./include/sys/zfs_context.h:95,
                 from module/zfs/vdev.c:36:
/usr/include/string.h:512:15: note: in a call to function 'strlcat' declared with attribute 'access (read_write, 1, 3)'
  512 | extern size_t strlcat (char *__restrict __dest,
      |               ^~~~~~~
  CC       module/zfs/libzpool_la-vdev_removal.lo
cc1: all warnings being treated as errors