rev:解决模型数据为空时，编辑流程出错

wms_pro/qd/src/views/wms/flow_manage/logicflow/FlowDesigner.vue

@@ -94,6 +94,7 @@ export default {
         left: 0
       },
       id: null,
+      initNodes: {"nodes": [], "edges": []},
       nodeData: null,
       addClickNode: null,
       clickNode: null,
@@ -224,7 +225,11 @@ export default {
      */
     $_render(row) {
       this.id = row.id
-      this.lf.render(JSON.parse(row.model_editor_json))
+      if (!row.model_editor_json) {
+        this.lf.render(this.initNodes)
+      } else {
+        this.lf.render(JSON.parse(row.model_editor_json))
+      }
       this.$_LfEvent()
     },
     $_getData() {