Add warning for missing data before 2018

DataImporter.py

@@ -43,6 +43,9 @@ class DataImporter(DataHandler, ABC):
         if weather is True and sessionIdentifier.year < self.firstFastF1Year:
             raise ValueError(f"Cannot fetch weather data for races before {self.firstFastF1Year} due to API limitations")
 
+        if sessionIdentifier.year < self.firstFastF1Year:
+            print(f"WARNING: No FastF1 data available before {self.firstFastF1Year}, using Jolpica data instead. Some expected data may be missing")
+
         session = fastf1.get_session(sessionIdentifier.year, sessionIdentifier.event, sessionIdentifier.sessionType)
         session.load(laps = laps, telemetry = telemetry, weather = weather, messages = messages)
         return session