bug fixes

src/app.vue

@@ -56,11 +56,12 @@ export default {
         const { code, data } = response
         if (code === 1) {
           this.sign = data
-          this.getSignDocument(data.flowid).then(() => {
-            if (!this.documentUrl) {
-              this.dialogVisible = true
-            }
-          })
+          data.flowid &&
+            this.getSignDocument(data.flowid).then(() => {
+              if (!this.documentUrl) {
+                this.dialogVisible = true
+              }
+            })
         } else {
           this.$message.error('处理签名失败')
         }