convert2hmi.py will accept hmi data

[PaulJWright]

convert2hmi.py will accept hmi data. Expected behaviour: the data should be recognised as HMI and skipped.

python convert2HMI.py --instrument mdi --data_path ../solarmag/ --destination ../solarmag/ --use_patches

2021-04-28 - 23:21:15 INFO __main__: Processing ../solarmag/mdi.fd_m_96m_lev182.20110331_013600_TAI.data.fits
2021-04-28 - 23:21:15 INFO __main__: Attempting inference on patches...
2021-04-28 - 23:21:26 INFO __main__: Success.
2021-04-28 - 23:21:26 INFO __main__: Processing ../solarmag/hmi.m_720s.20110331_013600_TAI.1.magnetogram.fits
2021-04-28 - 23:21:37 INFO __main__: Attempting inference on patches...
2021-04-28 - 23:24:25 INFO __main__: Success.
Traceback (most recent call last):
  File "convert2HMI.py", line 182, in <module>
    inferred_map = file_dset.create_new_map(inferred, scale_factor, args.add_noise, model_name, config_data, padding)
  File "/content/magnetograph_2HMI_converter/source/dataset.py", line 58, in create_new_map
    new_meta['r_sun'] = new_meta['r_sun'] * scale_factor
  File "/usr/local/lib/python3.7/dist-packages/sunpy/util/metadata.py", line 48, in __getitem__
    return OrderedDict.__getitem__(self, key.lower())
KeyError: 'r_sun'