fix error message dialog can be shown multi times

src/views/mobile/Unlock.vue

@@ -59,10 +59,17 @@ export default {
     },
     methods: {
         unlock() {
+            const app = this.$f7;
+            const $$ = app.$;
+
             if (!this.pinCodeValid) {
                 return;
             }
 
+            if ($$('.modal-in').length) {
+                return;
+            }
+
             const router = this.$f7router;
 
             try {