Fix undefined variable

[Ch00k]

I am using yubikey-manager as a library, and, when calling list_all_devices() on a Linux machine, that has no YubiKeys attached, I am getting the following exception:

Unable to list devices for connection
Traceback (most recent call last):
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/device.py", line 291, in list_all_devices
    for dev in _CONNECTION_LIST_MAPPING[connection_type]():
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/device.py", line 71, in inner
    return f()
           ^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/device.py", line 89, in list_ccid_devices
    return _list_ccid_devices()
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/pcsc/__init__.py", line 169, in list_devices
    for reader in list_readers():
                  ^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/pcsc/__init__.py", line 157, in list_readers
    return System.readers()
           ^^^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/smartcard/System.py", line 41, in readers
    return smartcard.reader.ReaderFactory.ReaderFactory.readers(groups)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/smartcard/reader/ReaderFactory.py", line 58, in readers
    zreaders += fm(groups)
                ^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/smartcard/pcsc/PCSCReader.py", line 111, in readers
    hcontext = PCSCContext().getContext()
               ^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/smartcard/pcsc/PCSCContext.py", line 56, in __init__
    self.renewContext()
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/smartcard/pcsc/PCSCContext.py", line 70, in renewContext
    PCSCContext.instance = PCSCContext.__PCSCContextSingleton()
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/smartcard/pcsc/PCSCContext.py", line 40, in __init__
    raise EstablishContextException(hresult)
smartcard.pcsc.PCSCExceptions.EstablishContextException: Failed to establish context: Service not available. (0x8010001D)
Unable to list devices for connection
Traceback (most recent call last):
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/device.py", line 291, in list_all_devices
    for dev in _CONNECTION_LIST_MAPPING[connection_type]():
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/device.py", line 71, in inner
    return f()
           ^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/device.py", line 101, in list_otp_devices
    return _list_otp_devices()
           ^^^^^^^^^^^^^^^^^^^
  File "/home/ay/projects/personal/yop/.direnv/python-3.12.1/lib/python3.12/site-packages/ykman/hid/linux.py", line 130, in list_devices
    _failed_cache.difference_update(hidraw)
                                    ^^^^^^
UnboundLocalError: cannot access local variable 'hidraw' where it is not associated with a value

I believe the root cause of the problem is wrong indentation, which this PR fixes.

[dainnilsson]

Thanks! You're correct, that's a bug. The fix was a bit different though, as can be seen in 5780253