Fix: Handle None attributes in history data (#2869)

Fixes crash: 'NoneType' object has no attribute 'pop'

Issue: Home Assistant history data can contain entries where 'attributes'
key exists but has a None value instead of a dictionary. This causes a
crash when trying to call .pop() on it.

Solution: Changed from checking key existence ('attributes' in entry) to
using entry.get('attributes') which returns None if the key doesn't exist
or if its value is None, and only processes attributes when it's truthy.

Reported by: daryl

Author: mgazza

apps/predbat/ha.py

@@ -148,7 +148,7 @@ def update_entity(self, entity_id, new_history_data):
 
         # Filter useless data from history data
         for entry in new_history_data:
-            if "attributes" in entry:
+            if entry.get("attributes"):
                 for attr in FILTER_ATTRIBUTES:
                     entry["attributes"].pop(attr, None)
             for entry_attr in FILTER_ENTRIES: