kivy error message

gui/kivy/uix/screens.py

@@ -257,6 +257,9 @@ class SendScreen(CScreen):
             outputs = self.payment_request.get_outputs()
         else:
             address = str(self.screen.address)
+            if not address:
+                self.app.show_error(_('No recipient. Please scan a Bitcoin address or a payment request'))
+                return
             if not bitcoin.is_address(address):
                 self.app.show_error(_('Invalid Bitcoin Address') + ':\n' + address)
                 return