Source file output not compatible with simulation input

[Nnayrod]

When generating a Source file using function source.Source.write(), the output file is not compatible with the filename attribute of simmetis.spectro.LMS:

Traceback (most recent call last):
  File "C:\Program Files\Python39\lib\site-packages\IPython\core\interactiveshell.py", line 3444, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-4-e5f0f441e6c9>", line 1, in <module>
    lms = sim.spectro.LMS("./test_data/stellar_spec_test.fits", "./notebooks/metis_spectro_LMS.config")
  File "\\wsl$\Debian\home\username\SimMETIS-0.3\simmetis\spectro.py", line 98, in __init__
    naxis3, naxis2, naxis1 = self.src_cube.shape
ValueError: not enough values to unpack (expected 3, got 2)

The header in the generated file is also different from the header of the test_data/LINE_3D_013.fits file given in example.
A method to generate a Source that can be read by LMS seems to be lacking.