kivy: support wallet is None

gui/kivy/main.kv

@@ -371,6 +371,7 @@ BoxLayout:
                 text: app.status
                 font_size: '22dp'
                 minimum_width: '1dp'
+                disabled: app.wallet is None
                 on_release: app.popup_dialog('status')
 
             ActionOverflow:

gui/kivy/main_window.py

@@ -522,6 +522,7 @@ class ElectrumWindow(App):
 
     def update_status(self, *dt):
         if not self.wallet:
+            self.status = _("No Wallet")
             return
         if self.network is None or not self.network.is_running():
             self.status = _("Offline")

gui/kivy/uix/screens.py

@@ -326,6 +326,8 @@ class ReceiveScreen(CScreen):
         self.screen.message = ''
 
     def get_new_address(self):
+        if not self.app.wallet:
+            return False
         addr = self.app.wallet.get_unused_address(None)
         if addr is None:
             return False
@@ -476,12 +478,10 @@ class RequestsScreen(CScreen):
     kvname = 'requests'
 
     def update(self):
-
         self.menu_actions = [('Show', self.do_show), ('Details', self.do_view), ('Delete', self.do_delete)]
-
         requests_list = self.screen.ids.requests_container
         requests_list.clear_widgets()
-        _list = self.app.wallet.get_sorted_requests(self.app.electrum_config)
+        _list = self.app.wallet.get_sorted_requests(self.app.electrum_config) if self.app.wallet else []
         for req in _list:
             address = req['address']
             timestamp = req.get('time', 0)