fix bug

src/components/RoleSelect.vue

@@ -48,7 +48,7 @@ export default {
   },
   methods: {
     select() {
-      if (this.selected.length > 1) {
+      if (this.multiple && this.selected.length > 1) {
         this.selected = this.selected.splice(1);
       }
       this.$emit("input", this.selected);