fix dbb cli

plugins/digitalbitbox/cmdline.py

@@ -1,3 +1,4 @@
+from electrum.plugins import hook
 from .digitalbitbox import DigitalBitboxPlugin
 from ..hw_wallet import CmdLineHandler
 

plugins/hw_wallet/cmdline.py

@@ -29,7 +29,7 @@ class CmdLineHandler:
     def stop(self):
         pass
 
-    def show_message(self, msg, on_cancel):
+    def show_message(self, msg, on_cancel=None):
         print_msg(msg)
 
     def update_status(self, b):