Error in calling `fftn` with an empty `axes`

[vtavana]

Following example returns an error

import mkl_fft.interfaces as mfi, numpy
b=numpy.array([[5, 7, 6, 5], [4, 6, 4, 8], [9, 3, 7, 5]], dtype=numpy.float32)
mfi.numpy_fft.fftn(b, axes=(), s=None, norm="forward")
# TypeError: copyto() argument 1 must be numpy.ndarray, not numpy.complex64

while NumPy works correctly

import numpy
b=numpy.array([[5, 7, 6, 5], [4, 6, 4, 8], [9, 3, 7, 5]], dtype=numpy.float32)
numpy.fft.fftn(b, axes=(), s=None, norm="forward")
# array([[5., 7., 6., 5.],
#       [4., 6., 4., 8.],
#       [9., 3., 7., 5.]], dtype=float32)

dtype of input array plays a role here. if dtype=numpy.int64, both NumPy and mfi.numpy_fft returns the same result.

[vtavana]

was resolved as part of #139