einx operation on zero-sized tensors

[isty2e]

When working with some types of data, I need to reshape arrays with zero elements. For example,

import numpy as np
import einx
import einops

arr = np.zeros((0, 0))

# numpy version - This works
reshaped_arr = np.expand_dims(arr, 0)

# einops version - This works as well
reshaped_arr_einops = einops.rearrange(arr, "... -> 1 ...")

# einx version - This does not
reshaped_arr_einx = einx.rearrange("... -> 1 ...", arr)

The error is:

----> 1 einx.rearrange("... -> () ...", arr)

File /path/to/lib/python3.10/site-packages/einx/traceback_util.py:71, in filter.<locals>.func_with_reraise(*args, **kwargs)
     69 except Exception as e:
     70     tb = _filter_tb(e.__traceback__)
---> 71     raise e.with_traceback(tb) from None
     72 finally:
     73     del tb

SolveValueException: Failed to solve values of expressions. Axis '_anonymous_ellipsis_axis.0' has value 0 <= 0
Input:
    '_anonymous_ellipsis_axis.0 _anonymous_ellipsis_axis.1 = 0 0'
    '() _anonymous_ellipsis_axis.0 _anonymous_ellipsis_axis.1 = None