修复bug

src/graphic/Controls/MoveLine.js

@@ -96,9 +96,11 @@ export default class MoveLine {
     let endPoint = dataService.getPoint(line.endId);
 
     let baseLine = dataService.getLine(Settings.baseLineId);
-    let baseStartPoint = dataService.getPoint(baseLine.startId);
-    let baseEndPoint = dataService.getPoint(baseLine.endId);
-    baseLine = mathUtil.createLine1(baseStartPoint, baseEndPoint);
+    if (baseLine) {
+      let baseStartPoint = dataService.getPoint(baseLine.startId);
+      let baseEndPoint = dataService.getPoint(baseLine.endId);
+      baseLine = mathUtil.createLine1(baseStartPoint, baseEndPoint);
+    }
 
     //垂直移动，直角定位法只支持定位线的拖拽
     if (