Raise issue with PPDD about empty midi files

[JamesOwers]

Get in touch with Tom and tell him about empty midi files:

onverting midi from PPDDSep2018Monophonic to csv at PPDDSep2018Monophonic:  14%|████████▉                                                      | 1582/11100 [01:45<07:07, 22.29it/s]WARNING: the midi file located at /Users/kungfujam/git/midi_degradation_toolkit/input_data/midi/PPDDSep2018Monophonic/c2dd8855-5ca3-4f43-b1c0-3c1bab1967e5.mid is empty. Returning None.
Converting midi from PPDDSep2018Monophonic to csv at PPDDSep2018Monophonic:  32%|████████████████████                                           | 3538/11100 [02:53<02:50, 44.25it/s]WARNING: the midi file located at /Users/kungfujam/git/midi_degradation_toolkit/input_data/midi/PPDDSep2018Monophonic/8774f407-9aa6-4bd5-9c9c-5c65c860d139.mid is empty. Returning None.
Converting midi from PPDDSep2018Monophonic to csv at PPDDSep2018Monophonic:  39%|████████████████████████▌                                      | 4319/11100 [03:11<04:06, 27.46it/s]WARNING: the midi file located at /Users/kungfujam/git/midi_degradation_toolkit/input_data/midi/PPDDSep2018Monophonic/35afaf73-d77e-4540-8bd4-e76be8dd5dbe.mid is empty. Returning None.
Converting midi from PPDDSep2018Monophonic to csv at PPDDSep2018Monophonic:  57%|████████████████████████████████████                           | 6348/11100 [04:19<04:11, 18.87it/s]WARNING: the midi file located at /Users/kungfujam/git/midi_degradation_toolkit/input_data/midi/PPDDSep2018Monophonic/fd732fe8-e956-4ac4-b4ee-0aecaa13a8ec.mid is empty. Returning None.
Converting midi from PPDDSep2018Monophonic to csv at PPDDSep2018Monophonic:  58%|████████████████████████████████████▍                          | 6425/11100 [04:23<05:10, 15.06it/s]WARNING: the midi file located at /Users/kungfujam/git/midi_degradation_toolkit/input_data/midi/PPDDSep2018Monophonic/696eeaba-4ae9-4664-98c8-8346e52d574e.mid is empty. Returning None.
Converting midi from PPDDSep2018Monophonic to csv at PPDDSep2018Monophonic:  80%|██████████████████████████████████████████████████▎            | 8863/11100 [06:33<02:48, 13.29it/s]WARNING: the midi file located at /Users/kungfujam/git/midi_degradation_toolkit/input_data/midi/PPDDSep2018Monophonic/afada301-d0a9-42db-af6d-792bed9af819.mid is empty. Returning None.