Raise error if ClassLabel names is not python list (#5359)

* Raise error if ClassLabel names is not python list

* Change to accepting Sequence for names

* Replace `ValueError` with `TypeError`

Co-authored-by: Mario Šaško <mariosasko777@gmail.com>

src/datasets/features/features.py

@@ -19,6 +19,7 @@
 import re
 import sys
 from collections.abc import Iterable, Mapping
+from collections.abc import Sequence as SequenceABC
 from dataclasses import InitVar, dataclass, field, fields
 from functools import reduce, wraps
 from operator import mul
@@ -944,6 +945,8 @@ def __post_init__(self, num_classes, names_file):
                 self.names = [str(i) for i in range(self.num_classes)]
             else:
                 raise ValueError("Please provide either num_classes, names or names_file.")
+        elif not isinstance(self.names, SequenceABC):
+            raise TypeError(f"Please provide names as a list, is {type(self.names)}")
         # Set self.num_classes
         if self.num_classes is None:
             self.num_classes = len(self.names)

tests/features/test_features.py

@@ -287,6 +287,8 @@ def test_classlabel_init(tmp_path_factory):
         classlabel = ClassLabel(names=names, names_file=names_file)
     with pytest.raises(ValueError):
         classlabel = ClassLabel()
+    with pytest.raises(TypeError):
+        classlabel = ClassLabel(names=np.array(names))
 
 
 def test_classlabel_str2int():