# Buggy code
def ensure_sequence_of_iterables(obj, length: Optional[int] = None):
    """Ensure that ``obj`` behaves like a (nested) sequence of iterables.

    If length is provided and the object is already a sequence of iterables,
    a ValueError will be raised if ``len(obj) != length``.

    Parameters
    ----------
    obj : Any
        the object to check
    length : int, optional
        If provided, assert that obj has len ``length``, by default None

    Returns
    -------
    iterable
        nested sequence of iterables, or an itertools.repeat instance

    Examples
    --------
    In [1]: ensure_sequence_of_iterables([1, 2])
    Out[1]: repeat([1, 2])

    In [2]: ensure_sequence_of_iterables([(1, 2), (3, 4)])
    Out[2]: [(1, 2), (3, 4)]

    In [3]: ensure_sequence_of_iterables({'a':1})
    Out[3]: repeat({'a': 1})

    In [4]: ensure_sequence_of_iterables(None)
    Out[4]: repeat(None)
    """
    if obj and is_sequence(obj) and is_iterable(obj[0]):
        if length is not None and len(obj) != length:
            raise ValueError(f"length of {obj} must equal {length}")
        return obj
    return itertools.repeat(obj)


# Traceback (IndexError)
ERROR:root:Unhandled exception:
Traceback (most recent call last):
File "C:\miniconda3\envs\bc\lib\site-packages\napari\_qt\event_loop.py", line 79, in gui_qt
yield app
File "<ipython-input-185-65466d9eb63b>", line 15, in <module>
viewer.add_image(
File "C:\miniconda3\envs\bc\lib\site-packages\napari\components\viewer_model.py", line 776, in add_image
layer = self.add_layer(image_class(image, **i_kwargs))
File "C:\miniconda3\envs\bc\lib\site-packages\napari\layers\image\image.py", line 209, in __init__
super().__init__(
File "C:\miniconda3\envs\bc\lib\site-packages\napari\layers\intensity_mixin.py", line 22, in __init__
super().__init__(*args, **kwargs)
File "C:\miniconda3\envs\bc\lib\site-packages\napari\layers\base\base.py", line 224, in __init__
data2world_transform = Affine(
File "C:\miniconda3\envs\bc\lib\site-packages\napari\utils\transforms\transforms.py", line 313, in __init__
linear_matrix = affine_matrix[:-1, :-1]
IndexError: too many indices for array: array is 1-dimensional, but 2 were indexed

# Fixed code
def ensure_sequence_of_iterables(obj, length: Optional[int] = None):
    """Ensure that ``obj`` behaves like a (nested) sequence of iterables.

    If length is provided and the object is already a sequence of iterables,
    a ValueError will be raised if ``len(obj) != length``.

    Parameters
    ----------
    obj : Any
        the object to check
    length : int, optional
        If provided, assert that obj has len ``length``, by default None

    Returns
    -------
    iterable
        nested sequence of iterables, or an itertools.repeat instance

    Examples
    --------
    In [1]: ensure_sequence_of_iterables([1, 2])
    Out[1]: repeat([1, 2])

    In [2]: ensure_sequence_of_iterables([(1, 2), (3, 4)])
    Out[2]: [(1, 2), (3, 4)]

    In [3]: ensure_sequence_of_iterables({'a':1})
    Out[3]: repeat({'a': 1})

    In [4]: ensure_sequence_of_iterables(None)
    Out[4]: repeat(None)
    """

    if obj is not None and is_sequence(obj) and is_iterable(obj[0]):
        if length is not None and len(obj) != length:
            raise ValueError(f"length of {obj} must equal {length}")
        return obj
    return itertools.repeat(obj)