日常报错、[Vue warn]: Invalid prop: type check failed for prop "multiple". Expected Boolean, got String.

VUE报错如下：
[Vue warn]: Invalid prop: type check failed for prop “multiple”. Expected Boolean, got String.
意思是期望的数据类型是boolean 类型，却被我定义成了字符串、
仔细看了下multiple这个组件属性、

log.js?4244:23 [HMR] Waiting for update signal from WDS...
backend.js:10619  vue-devtools  Detected Vue v2.5.16 
vue.esm.js?efeb:591 [Vue warn]: Invalid prop: type check failed for prop "multiple". Expected Boolean, got String.

found in

--->  at src\components\cascader\Cascader.vue
       
          at src\pages\item\MyBrandForm.vue
           
             
               
                  at src\pages\item\MyBrand.vue
                   
                     
                        at src\pages\Layout.vue
                          at src\App.vue
                           

原来是这样的、确实被定义成了字符串、

修改，把multiple后面的都去掉后、不再报错、其默认是true
并且、v-model 绑定的数据和multiple 要求的数据类型要一致、
v-model 绑定的是categories 是一个数组、那么 multiple 就是多个，其值是true ，刷新页面F12如下：