biosigIO 1.1.7

biosigIO 1.1.7

Typed read-error hierarchy (biosigio.exceptions)

biosigIO previously raised a generic ValueError for every read failure, so a
caller could not tell why a recording failed to load — a trial-averaged
derivative, a truncated file, and an unsupported format were indistinguishable.

This release adds a typed hierarchy so callers can classify the failure and
surface a specific reason (the NEMAR Zarr viewer uses this to explain why a
recording has no viewer instead of a blank "not available"):

• BiosigIOError — base; every error carries a stable .code.
• UnsupportedFormatError (unsupported_format)
• FileReadError (file_read_error) — generic fallback for a recognized format
  that still couldn't be read.
• NotContinuousRecordingError (not_continuous) — evoked *-ave.fif / epoched
  *-epo.fif derivatives: valid data, but no continuous time series.
• CorruptFileError (corrupt_or_truncated) — truncated/non-compliant files,
  incomplete CTF .meg4, or an incomplete split chain.
• EmptyRecordingError (empty_recording)
• MixedSamplingRateError (mixed_sampling_rate)
• classify_read_error(exc, filepath) maps a low-level MNE/pyedflib failure to
  the right type (shared by the importers).
• REASONS: code → default user-facing copy.

The MEG, EDF, BrainVision, and EEGLAB importers now raise these typed errors;
_infer_importer raises UnsupportedFormatError for unknown extensions.

Backward compatibility

BiosigIOError subclasses ValueError, so existing except ValueError /
pytest.raises(ValueError) callers keep working unchanged. The EDF mixed-rate
policy error is now MixedSamplingRateError (still a ValueError, same message).

Tests

Real-file verification (no mocks) for each NEMAR failure mode: a real MNE evoked
-ave.fif → not_continuous, an incomplete split-FIF chain → corrupt, a truncated
CTF .meg4 → corrupt, a truncated EDF → corrupt, plus classifier units and
back-compat assertions.