Add fix KazanExpress#589

Author: tbl0605

lib/vue-simple-suggest.vue

@@ -390,7 +390,7 @@ export default {
       })
     },
     select(item) {
-      if (this.selected !== item || (this.nullableSelect && !item)) {
+      if ((item && this.selected !== item) || (this.nullableSelect && !item)) {
         this.selected = item
         this.$emit('update:modelSelect', item)
         // For backward compatibility: