Fix TypeError in current_temperature if no temperature is known. (#22112)

Don't set opentherm_gw climate temperatures to 0 on init.

homeassistant/components/opentherm_gw/climate.py

@@ -37,8 +37,8 @@ class OpenThermGateway(ClimateDevice):
         self.floor_temp = config.get(CONF_FLOOR_TEMP)
         self.temp_precision = config.get(CONF_PRECISION)
         self._current_operation = STATE_IDLE
-        self._current_temperature = 0.0
-        self._target_temperature = 0.0
+        self._current_temperature = None
+        self._target_temperature = None
         self._away_mode_a = None
         self._away_mode_b = None
         self._away_state_a = False
@@ -124,6 +124,8 @@ class OpenThermGateway(ClimateDevice):
     @property
     def current_temperature(self):
         """Return the current temperature."""
+        if self._current_temperature is None:
+            return
         if self.floor_temp is True:
             if self.temp_precision == PRECISION_HALVES:
                 return int(2 * self._current_temperature) / 2