diff --git a/src/drawApp/jkApp.ts b/src/drawApp/jkApp.ts
index e3a1933..5df8a5a 100644
--- a/src/drawApp/jkApp.ts
+++ b/src/drawApp/jkApp.ts
@@ -184,14 +184,14 @@ export async function loadLinkDatas(app: IDrawApp) {
       length: link.length,
       index: link.index,
       aRelatedRef: new graphicData.RelatedRef({
-        id: link.aRelatedRef.id,
-        deviceType: link.aRelatedRef.deviceType,
-        devicePort: link.aRelatedRef.devicePort || 0,
+        id: link.aRelatedRef?.id,
+        deviceType: link.aRelatedRef?.deviceType,
+        devicePort: link.aRelatedRef?.devicePort || 0,
       }),
       bRelatedRef: new graphicData.RelatedRef({
-        id: link.bRelatedRef.id,
-        deviceType: link.bRelatedRef.deviceType,
-        devicePort: link.bRelatedRef.devicePort || 0,
+        id: link.bRelatedRef?.id,
+        deviceType: link.bRelatedRef?.deviceType,
+        devicePort: link.bRelatedRef?.devicePort || 0,
       }),
       devicePositions: ((): graphicData.CalculateLink.DevicePosition[] => {
         const dps: graphicData.CalculateLink.DevicePosition[] = [];