Fix import handling for filelock dependency

doc/whats_new.rst

@@ -56,6 +56,7 @@ Detailed list of changes
 
 - Fixed a bug that modified the name and help message of some of the available commands, by `Alex Lopez Marquez`_ (:gh:`1441`)
 - Updated MEG/iEEG writers to satisfy the stricter checks in the latest BIDS validator releases: BTi/4D run folders now retain their ``.pdf`` suffix (falling back to the legacy naming when an older validator is detected), KIT marker files encode the run via the ``acq`` entity instead of ``run``, datasets lacking iEEG montages receive placeholder ``electrodes.tsv``/``coordsystem.json`` files, and the ``AssociatedEmptyRoom`` entry stores dataset-relative paths  by `Bruno Aristimunha`_ (:gh:`1449`)
+- Made the lock helpers skip reference counting when the optional ``filelock`` dependency is missing, preventing spurious ``AttributeError`` crashes during reads, by `Bruno Aristimunha`_ (:gh:`1469`)
 - Fixed a bug in :func:`mne_bids.read_raw_bids` that caused it to fail when reading BIDS datasets where the acquisition time was specified in local time rather than UTC only in Windows, by `Bruno Aristimunha`_ (:gh:`1452`)
 
 ⚕️ Code health

mne_bids/_fileio.py

@@ -190,7 +190,7 @@ def _increment_lock_refcount(file_path):
     refcount_lock_path = Path(f"{refcount_path}.lock")
 
     filelock = _soft_import("filelock", purpose="lock refcounting", strict=False)
-    if filelock is None:
+    if not filelock:
         return
 
     refcount_lock = filelock.FileLock(str(refcount_lock_path), timeout=5.0)
@@ -254,7 +254,7 @@ def _decrement_and_cleanup_lock_file(file_path):
         return
 
     filelock = _soft_import("filelock", purpose="lock refcounting", strict=False)
-    if filelock is None:
+    if not filelock:
         return
 
     refcount_lock = filelock.FileLock(str(refcount_lock_path), timeout=5.0)

mne_bids/tests/test_tsv_handler.py

@@ -7,6 +7,7 @@
 
 import pytest
 
+import mne_bids._fileio as _fileio
 from mne_bids.tsv_handler import (
     _combine_rows,
     _contains_row,
@@ -75,6 +76,23 @@ def test_tsv_handler(tmp_path):
     d = _drop(d, "n/a", "trial_type")
 
 
+def test_to_tsv_without_filelock(monkeypatch, tmp_path):
+    """Ensure TSV writes succeed when filelock is unavailable."""
+    data = odict(a=[1, 2], b=["five", "six"])
+    tsv_path = tmp_path / "file.tsv"
+    lock_path = tsv_path.parent / f"{tsv_path.name}.lock"
+    refcount_path = tsv_path.parent / f"{tsv_path.name}.lock.refcount"
+
+    monkeypatch.setattr(_fileio, "_soft_import", lambda *args, **kwargs: None)
+
+    _to_tsv(data, tsv_path)
+
+    assert tsv_path.exists()
+    assert tsv_path.read_text().strip()
+    assert not lock_path.exists()
+    assert not refcount_path.exists()
+
+
 def test_contains_row_different_types():
     """Test that _contains_row() can handle different dtypes without warning.