Error in make_transfers

[mildfuzz]

I can see transfer stategy and team selection, but then it falls over with this:

Traceback (most recent call last):
  File "/home/john.farrow/miniconda3/envs/airsenalenv/bin/airsenal_run_pipeline", line 8, in <module>
    sys.exit(run_pipeline())
             ^^^^^^^^^^^^^^
  File "/home/john.farrow/miniconda3/envs/airsenalenv/lib/python3.12/site-packages/click/core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/john.farrow/miniconda3/envs/airsenalenv/lib/python3.12/site-packages/click/core.py", line 1078, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/home/john.farrow/miniconda3/envs/airsenalenv/lib/python3.12/site-packages/click/core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/john.farrow/miniconda3/envs/airsenalenv/lib/python3.12/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/john.farrow/miniconda3/envs/airsenalenv/lib/python3.12/site-packages/airsenal/scripts/airsenal_run_pipeline.py", line 240, in run_pipeline
    transfers_ok = make_transfers(fpl_team_id)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/john.farrow/miniconda3/envs/airsenalenv/lib/python3.12/site-packages/airsenal/scripts/make_transfers.py", line 324, in make_transfers
    post_transfer_bank = deduct_transfer_price(pre_transfer_bank, priced_transfers)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/john.farrow/miniconda3/envs/airsenalenv/lib/python3.12/site-packages/airsenal/scripts/make_transfers.py", line 53, in deduct_transfer_price
    transfer["selling_price"] - transfer["purchase_price"]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
TypeError: unsupported operand type(s) for -: 'NoneType' and 'int'