trezor: Default to empty string passphrase

If the passphrase is not provided and passphrase protection is enabled,
default to the empty string.

hwilib/devices/trezor.py

@@ -289,6 +289,8 @@ def __init__(
  sim_path: str = SIMULATOR_PATH,
  model: Optional[TrezorModel] = None
  ) -> None:
+ if password is None:
+ password = ""
  super(TrezorClient, self).__init__(path, password, expert, chain)
  self.simulator = False
  transport = get_path_transport(path, hid_ids, webusb_ids, sim_path)
@@ -879,7 +881,7 @@ def enumerate(password: Optional[str] = None) -> List[Dict[str, Any]]:
  if d_data['needs_pin_sent']:
  raise DeviceNotReadyError('Trezor is locked. Unlock by using \'promptpin\' and then \'sendpin\'.')
  if d_data['needs_passphrase_sent'] and password is None:
- raise DeviceNotReadyError("Passphrase needs to be specified before the fingerprint information can be retrieved")
+ d_data["warnings"] = [["Passphrase protection enabled but passphrase was not provided. Using default passphrase of the empty string (\"\")"]]
  if client.client.features.initialized:
  d_data['fingerprint'] = client.get_master_fingerprint().hex()
  d_data['needs_passphrase_sent'] = False # Passphrase is always needed for the above to have worked, so it's already sent