trezor/keepkey: better handling of exceptions during device initialization

notably Trezor T is returning a different msg type when trying to get an xpub from an uninitialized device, which we are not handling. instead we should just realise ourselves that we did not initialize the device

plugins/keepkey/keepkey.py

@@ -181,19 +181,26 @@ class KeepKeyPlugin(HW_PluginBase):
             t = threading.Thread(target=self._initialize_device_safe, args=(settings, method, device_id, wizard, handler))
             t.setDaemon(True)
             t.start()
-            wizard.loop.exec_()
+            exit_code = wizard.loop.exec_()
+            if exit_code != 0:
+                # this method (initialize_device) was called with the expectation
+                # of leaving the device in an initialized state when finishing.
+                # signal that this is not the case:
+                raise UserCancelled()
         wizard.choice_dialog(title=_('Initialize Device'), message=msg, choices=choices, run_next=f)
 
     def _initialize_device_safe(self, settings, method, device_id, wizard, handler):
+        exit_code = 0
         try:
             self._initialize_device(settings, method, device_id, wizard, handler)
         except UserCancelled:
-            pass
+            exit_code = 1
         except BaseException as e:
             traceback.print_exc(file=sys.stderr)
             handler.show_error(str(e))
+            exit_code = 1
         finally:
-            wizard.loop.exit(0)
+            wizard.loop.exit(exit_code)
 
     def _initialize_device(self, settings, method, device_id, wizard, handler):
         item, label, pin_protection, passphrase_protection = settings

plugins/trezor/trezor.py

@@ -202,19 +202,26 @@ class TrezorPlugin(HW_PluginBase):
             t = threading.Thread(target=self._initialize_device_safe, args=(settings, method, device_id, wizard, handler))
             t.setDaemon(True)
             t.start()
-            wizard.loop.exec_()
+            exit_code = wizard.loop.exec_()
+            if exit_code != 0:
+                # this method (initialize_device) was called with the expectation
+                # of leaving the device in an initialized state when finishing.
+                # signal that this is not the case:
+                raise UserCancelled()
         wizard.choice_dialog(title=_('Initialize Device'), message=msg, choices=choices, run_next=f)
 
     def _initialize_device_safe(self, settings, method, device_id, wizard, handler):
+        exit_code = 0
         try:
             self._initialize_device(settings, method, device_id, wizard, handler)
         except UserCancelled:
-            pass
+            exit_code = 1
         except BaseException as e:
             traceback.print_exc(file=sys.stderr)
             handler.show_error(str(e))
+            exit_code = 1
         finally:
-            wizard.loop.exit(0)
+            wizard.loop.exit(exit_code)
 
     def _initialize_device(self, settings, method, device_id, wizard, handler):
         item, label, pin_protection, passphrase_protection, recovery_type = settings