_energy_log_records_load_from_cache(): guard for empty log

Author: bouwew

plugwise_usb/nodes/circle.py

@@ -524,6 +524,9 @@ async def _energy_log_records_load_from_cache(self) -> bool:
             return False
         restored_logs: dict[int, list[int]] = {}
         log_data = cache_data.split("|")
+        if len(log_data) == 0:
+            return False
+
         for log_record in log_data:
             log_fields = log_record.split(":")
             if len(log_fields) == 4:
@@ -555,6 +558,7 @@ async def _energy_log_records_load_from_cache(self) -> bool:
         # Create task to retrieve remaining (missing) logs
         if self._energy_counters.log_addresses_missing is None:
             return False
+
         if len(self._energy_counters.log_addresses_missing) > 0:
             if self._retrieve_energy_logs_task is not None:
                 if not self._retrieve_energy_logs_task.done():
@@ -563,6 +567,7 @@ async def _energy_log_records_load_from_cache(self) -> bool:
                 self.get_missing_energy_logs()
             )
             return False
+
         return True
 
     async def _energy_log_records_save_to_cache(self) -> None: