fixed runtime error on postevent dashboard (#140)

Problem
- would get runtime error when trying to filter hospital transports and deprture_dest is null

Solution
- added a check to see if departure_dest is null and if so, return false

Ticket:
N/A

Documentation:
N/A

Tests
- tested on local machine and no longer get runtime error

app/web/utils/postfestivalDashboard.ts

@@ -1019,7 +1019,7 @@ export function calculateTransportLosListData(
   patientEncounters: PatientEncounterRow[]
 ): LengthOfStayTransportItem[] {
   const hospitalTransports = patientEncounters.filter((encounter) =>
-    encounter.departure_dest.toLowerCase().includes("hospital")
+    encounter.departure_dest?.toLowerCase().includes("hospital")
   );
 
   // Helper function to combine date and time in UTC