Merge branch 'fly-out-nav-mousepos-error' into 'master'

Fixed fly-out error if mousePos array is empty

See merge request gitlab-org/gitlab-ce!14338

app/assets/javascripts/fly_out_nav.js

@@ -34,7 +34,7 @@ export const canShowActiveSubItems = (el) => {
 export const canShowSubItems = () => bp.getBreakpointSize() === 'sm' || bp.getBreakpointSize() === 'md' || bp.getBreakpointSize() === 'lg';
 
 export const getHideSubItemsInterval = () => {
-  if (!currentOpenMenu) return 0;
+  if (!currentOpenMenu || !mousePos.length) return 0;
 
   const currentMousePos = mousePos[mousePos.length - 1];
   const prevMousePos = mousePos[0];

spec/javascripts/fly_out_nav_spec.js

@@ -73,6 +73,12 @@ describe('Fly out sidebar navigation', () => {
       ).toBe(0);
     });
 
+    it('returns 0 if mousePos is empty', () => {
+      expect(
+        getHideSubItemsInterval(),
+      ).toBe(0);
+    });
+
     it('returns 0 when mouse above sub-items', () => {
       showSubLevelItems(el);
       documentMouseMove({