examples/bluetooth: Fix check for _conn_handle being None.

Fixes issue #10755.

Signed-off-by: Damien George <damien@micropython.org>

examples/bluetooth/ble_simple_central.py

@@ -179,7 +179,7 @@ class BLESimpleCentral:
 
     # Disconnect from current device.
     def disconnect(self):
-        if not self._conn_handle:
+        if self._conn_handle is None:
             return
         self._ble.gap_disconnect(self._conn_handle)
         self._reset()

examples/bluetooth/ble_temperature_central.py

@@ -196,7 +196,7 @@ class BLETemperatureCentral:
 
     # Disconnect from current device.
     def disconnect(self):
-        if not self._conn_handle:
+        if self._conn_handle is None:
             return
         self._ble.gap_disconnect(self._conn_handle)
         self._reset()