fix getting the filename from the keystore option.

apps/pair.py

@@ -366,7 +366,7 @@ async def pair(
     '--request', is_flag=True, help='Request that the connecting peer initiate pairing'
 )
 @click.option('--print-keys', is_flag=True, help='Print the bond keys before pairing')
-@click.option('--keystore-file', help='File in which to store the pairing keys')
+@click.option('--keystore-file', metavar='<filename>', help='File in which to store the pairing keys')
 @click.argument('device-config')
 @click.argument('hci_transport')
 @click.argument('address-or-name', required=False)

bumble/keys.py

@@ -217,7 +217,7 @@ class JsonKeyStore(KeyStore):
         params = device_config.keystore.split(':', 1)[1:]
         namespace = str(device_config.address)
         if params:
-            filename = params[1]
+            filename = params[0]
         else:
             filename = None