Handle missing entity

homeassistant/components/min_max/repairs.py

@@ -47,7 +47,8 @@ class MigrateToGroupSensorFlow(RepairsFlow):
         old_entity = entity_reg.async_get_entity_id(
             SENSOR_DOMAIN, DOMAIN, self.entry.entry_id
         )
-        assert old_entity
+        if not old_entity:
+            return self.async_abort(reason="entity_not_found")
 
         if user_input is not None:
             config = dict(self.entry.options)

homeassistant/components/min_max/strings.json

@@ -13,6 +13,9 @@
   "issues": {
     "migrate_to_group_sensor": {
       "fix_flow": {
+        "abort": {
+          "entity_not_found": "Entity could not be found, please restart repairing the issue."
+        },
         "step": {
           "migrate": {
             "description": "The Min/Max helper has been deprecated and {title} will be migrated to a group sensor when you click submit to fix this repair.",