Protect combine() from mixing 1/N-dimensional arguments.

src/biocutils/combine.py

@@ -18,7 +18,17 @@ def combine(*x: Any):
     Returns:
         A combined object, typically the same type as the first element in ``x``.
     """
-    if hasattr(x[0], "shape") and len(x[0].shape) > 1:
+    has_1d = False
+    has_nd = False
+    for y in x:
+        if hasattr(y, "shape") and len(y.shape) > 1:
+            has_nd = True
+        else:
+            has_1d = True
+
+    if has_nd and has_1d:
+        raise ValueError("cannot mix 1-dimensional and higher-dimensional objects in `combine`")
+    if has_nd:
         return combine_rows(*x)
     else:
         return combine_sequences(*x)

tests/test_combine.py

@@ -36,3 +36,7 @@ def test_basic_mixed_dense_array():
     y = np.array([4, 5, 6, 7]).reshape((2,2))
     zcomb = combine(x, y)
     assert zcomb.shape == (4, 2)
+
+    with pytest.raises(ValueError) as ex:
+        combine(x, [1,2,3,4])
+    assert str(ex.value).find("cannot mix") >= 0