[demianw]

What was wrong

scripts/cli_tract_math.py caught every TypeError raised while running an operation and reported it as a usage error, so bugs inside operations looked like wrong command lines. Reproduction on master (NumPy 2.5.4), where tract_bhattacharyya_coefficient has an internal TypeError (fixed separately in #143):

$ tract_math a.trk tract_bhattacharyya_coefficient 2 b.trk
Traceback (most recent call last):            # on stdout
  ...
TypeError: `bins` must be an integer, a string, or an array
usage: ...
tract_math: error:

Error: Wrong number of parameters for the operation

Also print(sys.stderr, "Error reading file ", ...) printed <_io.TextIOWrapper name='<stderr>' ...> Error reading file ... to stdout instead of writing to stderr.

The change

• cli_tract_math.main catches only TractMathWrongArgumentsError (already a TypeError subclass) and reports just its message through parser.error, without a traceback, since it is a usage error. Any other exception propagates with its normal traceback and message. The now unused traceback import is removed.
• Genuine wrong parameter counts still give a usage error: too few parameters were already rejected by the decorator, but too many parameters only failed as the TypeError of the operation call itself (e.g. tract_math t.trk count extra out.txt → count() takes 2 positional arguments but 3 were given). The decorator now checks the arguments with inspect.signature(func).bind(...) before calling the operation and raises TractMathWrongArgumentsError on a mismatch.
• print(..., file=sys.stderr) for the file reading error.

After the change, the command above shows the TypeError traceback from NumPy (exit status 1), while tract_math t.trk tract_volume (missing parameter) prints only tract_math: error: Wrong number of arguments for the operation... (exit status 2).

Behaviour change: errors inside operations are no longer reported as "Wrong number of parameters"; usage errors no longer print a traceback.

Testing

• New tests in tests/test_tract_math.py (pytest-console-scripts): missing and extra parameters give a usage error without a traceback; a TypeError raised inside an operation propagates out of main() instead of becoming a usage error; the file reading error goes to stderr. All four fail on master and pass here.
• python -m pytest -q -p no:cacheprovider tract_querier: 46 passed, 1 skipped (pre-existing unconditional skip in test_query_rewrite.py).

Merge order

Touches lines next to #138 (--force in scripts/cli_tract_math.py and decorator.py, which raises its overwrite message through TractMathWrongArgumentsError — with this PR that message is shown without a traceback) and #139 (decorator.py); textual conflicts only. Both #106 and #143 append tests to tests/test_tract_math.py. Independent of #143 otherwise.

Closes #106

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