php 版本冲突修改

app/Http/Controllers/ProcurementController.php

@@ -353,7 +353,7 @@ class ProcurementController extends Controller
         foreach ($procurements as $procurement){
             if (empty($procurement->procurementDeliveries))continue;
             $procurement->receive_amount=$procurement->procurementDeliveries->sum('amount');
-            $procurement->signed_at=$procurement->procurementDeliveries->first()['signed_at'];
+            $procurement->signed_at=$procurement->procurementDeliveries->first()['signed_at']??null;
         }
         return view('procurement/finance/procurementBill',compact('suppliers','materials','owners','paginateParams','procurements'));
     }
@@ -483,7 +483,7 @@ class ProcurementController extends Controller
         foreach ($procurements as $procurement){
             if (empty($procurement->procurementDeliveries))continue;
             $procurement->receive_amount=$procurement->procurementDeliveries->sum('receipt_amount');
-            $procurement->signed_at=$procurement->procurementDeliveries->first()['signed_at'];
+            $procurement->signed_at=$procurement->procurementDeliveries->first()['signed_at']??null;
         }
 
         $procurementStatus=Procurement::status;