DeviceMgr: don't mark client as failing if create_client() is None

Otherwise the exception raised by client.label() would seem important.

electrum/plugin.py

@@ -598,6 +598,8 @@ class DeviceMgr(ThreadJob):
                 continue
             try:
                 client = self.create_client(device, handler, plugin)
+                if not client:
+                    continue
                 label = client.label()
                 is_initialized = client.is_initialized()
                 soft_device_id = client.get_soft_device_id()
@@ -607,8 +609,6 @@ class DeviceMgr(ThreadJob):
                 if include_failing_clients:
                     infos.append(DeviceInfo(device=device, exception=e, plugin_name=plugin.name))
                 continue
-            if not client:
-                continue
             infos.append(DeviceInfo(device=device,
                                     label=label,
                                     initialized=is_initialized,