Fix tinymce component input watch wrong

Tinymce watch  input value 不正常

如果传入为空 Tinymce 不会进行刷新

src/components/Tinymce/index.vue

@@ -48,7 +48,8 @@ export default {
   },
   watch: {
     value(val) {
-      if (!this.hasChange && this.hasInit) {
+      if (val == null) {val = ''}
+      if (this.hasInit) {
         this.$nextTick(() => window.tinymce.get(this.tinymceId).setContent(val))
       }
     }