Merge branch 'kkloss-fix-getcomputedstyle-error-mounting-global-search-header' into 'master'

Fix getComputedStyle error when mounting global search header

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/169142



Merged-by: Tomas Bulva <tbulva@gitlab.com>
Approved-by: Tomas Bulva <tbulva@gitlab.com>
Co-authored-by: Kev Kloss <kkloss@gitlab.com>

app/assets/javascripts/super_sidebar/components/global_search/components/global_search_header_app.vue

@@ -40,8 +40,10 @@ export default {
     };
   },
   mounted() {
-    this.isNarrowScreen = isNarrowScreen(this.$refs?.buttonRoot);
-    isNarrowScreenAddListener(this.$refs?.buttonRoot, this.handleNarrowScreenChange);
+    if (this.$refs?.buttonRoot) {
+      this.isNarrowScreen = isNarrowScreen(this.$refs.buttonRoot);
+      isNarrowScreenAddListener(this.$refs.buttonRoot, this.handleNarrowScreenChange);
+    }
   },
   beforeDestroy() {
     isNarrowScreenRemoveListener(this.$refs.buttonRoot, this.handleNarrowScreenChange);