fix: empty budget limits

Author: soloam

custom_components/fireflyiii_integration/integrations/fireflyiii.py

@@ -626,7 +626,7 @@ async def budgets(self, ids=None, currency=None) -> FireflyiiiObjectBaseList:
             try:
                 start_limit = datetime.fromisoformat(limit_attributes.get("start"))
                 end_limit = datetime.fromisoformat(limit_attributes.get("end"))
-            except ValueError:
+            except (ValueError,  TypeError):
                 start_limit = None
                 end_limit = None