fix: check if TImeSeries initialized before testing dates

src/sirocco/core.py

@@ -159,16 +159,19 @@ def __setitem__(self, date: datetime, data: TimeSeriesObject) -> None:
             self.end_date = date
 
     def __getitem__(self, date: datetime) -> TimeSeriesObject:
+        if self.start_date is None:
+            msg = "TimeSeries still empty, cannot access by date"
+            raise ValueError(msg)
+        if date not in self._dict:
+            msg = f"date {date} not found"
+            raise KeyError(msg)
         if date < self.start_date or date > self.end_date:
             item = next(iter(self._dict.values()))
             msg = (
                 f"date {date} for item '{item.name}' is out of bounds [{self.start_date} - {self.end_date}], ignoring."
             )
             logger.warning(msg)
             return None
-        if date not in self._dict:
-            msg = f"date {date} not found"
-            raise KeyError(msg)
         return self._dict[date]
 
     def values(self) -> Iterator[TimeSeriesObject]: