diffoscope's odd UnicodeDecodeError error message: reason found

[Mark Millard via freebsd-current]

# diffoscope /.zfs/snapshot/2021-04-*-01:40:48-0/bin/sh
[...]
$<3/>2021-05-04 08:49:21 W: diffoscope.main: Fuzzy-matching is currently disabled as the "tlsh" module is unavailable.
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb7 in position 18: invalid start byte

Well, it turns out that the file name pattern was
incorrect and only matched one file.

By contrast:

# diffoscope /.zfs/snapshot/2021-04-*/bin/sh
$<3/>2021-05-04 11:05:25 W: diffoscope.main: Fuzzy-matching is currently disabled as the "tlsh" module is unavailable.

worked fine.

And making the "one file" status obvious:

# diffoscope c_tests/a.out
$<3/>2021-05-04 11:11:45 W: diffoscope.main: Fuzzy-matching is currently disabled as the "tlsh" module is unavailable.
$<3/>Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/diffoscope/main.py", line 745, in main
sys.exit(run_diffoscope(parsed_args))
File "/usr/local/lib/python3.7/site-packages/diffoscope/main.py", line 677, in run_diffoscope
difference = load_diff_from_path(path1)
File "/usr/local/lib/python3.7/site-packages/diffoscope/readers/__init__.py", line 31, in load_diff_from_path
return load_diff(codecs.getreader("utf-8")(fp), path)
File "/usr/local/lib/python3.7/site-packages/diffoscope/readers/__init__.py", line 35, in load_diff
return JSONReaderV1().load(fp, path)
File "/usr/local/lib/python3.7/site-packages/diffoscope/readers/json.py", line 33, in load
raw = json.load(fp)
File "/usr/local/lib/python3.7/json/__init__.py", line 293, in load
return loads(fp.read(),
File "/usr/local/lib/python3.7/codecs.py", line 504, in read
newchars, decodedbytes = self.decode(data, self.errors)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb7 in position 18: invalid start byte

Not exactly an obvious error message for the issue.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)