fix(@gms/gms-plugin-billexpand): 读取settings的时候额外判断一下避免报错

develop/@gms/gms-plugin-billexpand/src/control/signature-list.vue

@@ -50,9 +50,10 @@ export default {
   mounted() {
     this.tagId = window.nros.getCurrTag()
     window.GMS.vbus.$on(GLOBAL_EVENT.VERIFY_SIGNATURE_FAIL, this.loadVerifiedImage)
-
     let protectFields =
-      this.context.settings.content.signatureConfig
+      this.context.settings
+      && this.context.settings.content
+      && this.context.settings.content.signatureConfig
       && this.context.settings.content.signatureConfig.fields
     const masterTableName = this.context.bill.getTableType('masterName').name
     if (!protectFields || !protectFields.length) {