Fix bug & refacor the first/last stop determining

Fixed last stop determining function and at the same time
refactor both functions to use lodash's min and max functions.

Resolves HSLdevcom/jore4##1384

Author: HenrikHartiala

ui/src/hooks/routes/useExportRoutes.ts

@@ -29,7 +29,7 @@ export const useExportRoutes = () => {
         is_used_as_timing_point: boolean;
       }>(jp);
       return (
-        firstStop.is_used_as_timing_point && lastStop.is_used_as_timing_point
+        firstStop?.is_used_as_timing_point && lastStop?.is_used_as_timing_point
       );
     });
 

ui/src/utils/journeyPattern.ts

@@ -1,3 +1,5 @@
+import maxBy from 'lodash/maxBy';
+import minBy from 'lodash/minBy';
 import {
   JourneyPatternScheduledStopPointInJourneyPatternInsertInput,
   JourneyPatternStopFragment,
@@ -103,16 +105,9 @@ type JourneyPatternWithGenericReturnType<TType> = {
 export const extractJourneyPatternFirstStop = <TType>(
   journeyPattern: JourneyPatternWithGenericReturnType<TType>,
 ) => {
-  return journeyPattern.scheduled_stop_point_in_journey_patterns.reduce(
-    (minObj, currentObj) => {
-      if (
-        currentObj.scheduled_stop_point_sequence <
-        minObj.scheduled_stop_point_sequence
-      ) {
-        return currentObj;
-      }
-      return minObj;
-    },
+  return minBy(
+    journeyPattern.scheduled_stop_point_in_journey_patterns,
+    'scheduled_stop_point_sequence',
   );
 };
 
@@ -122,15 +117,8 @@ export const extractJourneyPatternFirstStop = <TType>(
 export const extractJourneyPatternLastStop = <TType>(
   journeyPattern: JourneyPatternWithGenericReturnType<TType>,
 ) => {
-  return journeyPattern.scheduled_stop_point_in_journey_patterns.reduce(
-    (minObj, currentObj) => {
-      if (
-        currentObj.scheduled_stop_point_sequence <
-        minObj.scheduled_stop_point_sequence
-      ) {
-        return currentObj;
-      }
-      return minObj;
-    },
+  return maxBy(
+    journeyPattern.scheduled_stop_point_in_journey_patterns,
+    'scheduled_stop_point_sequence',
   );
 };