syntax error with lone > or < as string in [ ] tests with -a or -o operators

[Emanuel Attila Czirai]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: x86_64-pc-linux-gnu-gcc
Compilation CFLAGS: -march=skylake -mtune=skylake -mprefer-vector-width=128
-O2 -pipe -frecord-gcc-switches -ggdb -fvar-tracking-assignments
-fno-omit-frame-pointer -ftrack-macro-expansion=2 -fstack-protector-all
-Wno-trigraphs -fno-schedule-insns2 -fno-delete-null-pointer-checks
-D_FORTIFY_SOURCE=2 -rdynamic -flifetime-dse=1
uname output: Linux i87k 6.8.2-gentoo-x86_64 #1 SMP Fri Apr  5 15:17:56
CEST 2024 x86_64 Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz GenuineIntel
GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.2
Patch Level: 26
Release Status: release

Description:
    the [ test with -n or -z on a string that's only the angle bracket char
followed by -a or -o operators, fails like:
bash: [: syntax error: `-n' unexpected

Repeat-By:

$ [ -n ">" -a -n "something" ] || echo hmm
bash: [: syntax error: `-n' unexpected
hmm

$ [ -n "${var:->}" -a -n "something" ] || echo hmm
bash: [: syntax error: `-n' unexpected
hmm

$ var=">"
$ [ -n "${var}" -a -n "something" ] || echo hmm bash: [: syntax error: `-n'
unexpected hmm

etc.

But the issue doesn't happen if it's more than one char in the string
that's tested for -n or -z, for example :

$ [ -n ">>" -a -n "something" ] || echo hmm
(no output, or error)

Note, the issue is present also in (current latest) FreeBSD's '/bin/sh' and
'bash' and `/bin/[`.

But doesn't happen on Gentoo's /usr/bin/[ which is from
sys-apps/coreutils-9.5::gentoo

$ /usr/bin/[ -n ">" -a -n "something" ] || echo hmm
(no output, or error)