revamp new trip flow

frontend/lib/utils/fetch_trip.dart

@@ -29,11 +29,10 @@ Dio dio = Dio(
 
 fetchTrip(
   Trip trip,
-  Future<UserPreferences> preferences,
+  UserPreferences preferences,
 ) async {
-  UserPreferences prefs = await preferences;
   Map<String, dynamic> data = {
-    "preferences": prefs.toJson(),
+    "preferences": preferences.toJson(),
     "start": trip.landmarks!.first.location,
   };
   String dataString = jsonEncode(data);
@@ -47,11 +46,16 @@ fetchTrip(
   // handle errors
   if (response.statusCode != 200) {
     trip.updateUUID("error");
-    if (response.data["detail"] != null) {
-      trip.updateError(response.data["detail"]);
-      log(response.data["detail"]);
-      // throw Exception(response.data["detail"]);
+    String errorDetail;
+    if (response.data.runtimeType == String) {
+      errorDetail = response.data;
+    } else {
+      errorDetail = response.data["detail"] ?? "Unknown error";
     }
+    trip.updateError(errorDetail);
+    log(errorDetail);
+    // Actualy no need to throw an exception, we can just log the error and let the user retry
+    // throw Exception(errorDetail);
   } else {
     Map<String, dynamic> json = response.data;