Raise for 0-d input

Author: mtsokol

numpy/_core/shape_base.py

@@ -524,6 +524,8 @@ def unstack(x, /, *, axis=0):
     np.True_
 
     """
+    if x.ndim == 0:
+        raise ValueError("Input array must be at least 1-d.")
     return tuple(_nx.moveaxis(x, axis, 0))
 
 # Internal functions to eliminate the overhead of repeated dispatch in one of

numpy/_core/tests/test_shape_base.py

@@ -520,6 +520,7 @@ def test_unstack():
 
     assert_raises(ValueError, np.unstack, a, axis=3)
     assert_raises(ValueError, np.unstack, a, axis=-4)
+    assert_raises(ValueError, np.unstack, np.array(0), axis=0)
 
 
 @pytest.mark.parametrize("axis", [0])