REFACTOR: Remove `_.isString`

REFACTOR: Remove _.isString

diff --git a/app/assets/javascripts/discourse/app/lib/autocomplete.js b/app/assets/javascripts/discourse/app/lib/autocomplete.js
index 47cde9a..2e5b690 100644
--- a/app/assets/javascripts/discourse/app/lib/autocomplete.js
+++ b/app/assets/javascripts/discourse/app/lib/autocomplete.js
@@ -473,7 +473,7 @@ export default function(options) {
           inputSelectedItems.push("");
         }
 
-        if (_.isString(inputSelectedItems[0]) && me.val().length > 0) {
+        if (typeof inputSelectedItems[0] === "string" && me.val().length > 0) {
           inputSelectedItems.pop();
           inputSelectedItems.push(me.val());
           if (options.onChangeItems) {

GitHub sha: e60d06d8

This commit appears in #10566 which was merged by eviltrout.