change contrat creation

apps/edr-freight-api/src/modules/train-scheduling/train-scheduling.service.ts

@@ -5635,9 +5635,12 @@ export class TrainSchedulingService {
       // --- validate additions: AVAILABLE, loose, standing in the train's yard ---
       const added: Wagon[] = [];
       for (const wagonId of addWagonIds) {
+        // No `relations` on this query: Postgres refuses FOR UPDATE through the
+        // nullable side of the wagonType LEFT JOIN ("FOR UPDATE cannot be
+        // applied to the nullable side of an outer join"). Lock the row alone,
+        // then attach its type with a separate unlocked lookup.
         const wagon = await manager.getRepository(Wagon).findOne({
           where: { id: wagonId },
-          relations: { wagonType: true },
           lock: { mode: 'pessimistic_write' },
         });
         if (!wagon) throw new NotFoundException(`Wagon ${wagonId} not found`);
@@ -5654,6 +5657,10 @@ export class TrainSchedulingService {
             `Wagon ${wagon.wagonNumber} is not in the train's yard — only wagons in the same yard can be coupled`,
           );
         }
+        wagon.wagonType =
+          (await manager
+            .getRepository(WagonType)
+            .findOne({ where: { id: wagon.wagonTypeId } })) ?? undefined;
         added.push(wagon);
       }