Update backend.py

Author: pierre-rouanet

src/reachy_mini/daemon/backend/robot/backend.py

@@ -514,16 +514,16 @@ def decode_hardware_error_byte(err_byte: int) -> list[str]:
             return [bits_to_error[b] for b in err_bits if b in bits_to_error]
 
         def check_voltage(
-            id,
+            id: int,
             allowed_max_voltage: float = 7.3,
         ) -> bool:
             assert self.c is not None, (
                 "Motor controller not initialized or already closed."
             )
             # https://emanual.robotis.com/docs/en/dxl/x/xl330-m288/#present-input-voltage
             resp_bytes = self.c.async_read_raw_bytes(id, 144, 2)
-            voltage = struct.unpack("h", bytes(resp_bytes))
-            voltage = voltage[0] / 10.0  # in Volts
+            resp = struct.unpack("h", bytes(resp_bytes))[0]
+            voltage: float = resp / 10.0  # in Volts
 
             return voltage > allowed_max_voltage