fix date retrieval for synthetic storm creation

Author: zacharyburnett

stormevents/stormevent.py

@@ -244,7 +244,7 @@ def start_date(self, start_date: datetime):
     @lru_cache(maxsize=None)
     def __data_start(self) -> datetime:
         data_start = self.__entry["start_date"]
-        if pandas.isna(data_start):
+        if pandas.isna(data_start) and not self.synthetic:
             data_start = VortexTrack.from_storm_name(self.name, self.year).start_date
         return data_start
 
@@ -269,7 +269,7 @@ def end_date(self, end_date: datetime):
     @lru_cache(maxsize=None)
     def __data_end(self) -> datetime:
         data_end = self.__entry["end_date"]
-        if pandas.isna(data_end):
+        if pandas.isna(data_end) and not self.synthetic:
             data_end = VortexTrack.from_storm_name(self.name, self.year).end_date
         return data_end