Remove suppress_ajax_navigation_errors feature flag

This commit removes the suppress_ajax_navigation_errors feature flag.
This flag was already enabled by default, so this has no effect on the
product.

app/assets/javascripts/lib/utils/axios_utils.js

@@ -33,11 +33,9 @@ window.addEventListener('beforeunload', () => {
 
 // Ignore AJAX errors caused by requests
 // being cancelled due to browser navigation
-const { gon } = window;
-const featureFlagEnabled = gon && gon.features && gon.features.suppressAjaxNavigationErrors;
 axios.interceptors.response.use(
   response => response,
-  err => suppressAjaxErrorsDuringNavigation(err, isUserNavigating, featureFlagEnabled),
+  err => suppressAjaxErrorsDuringNavigation(err, isUserNavigating),
 );
 
 export default axios;

app/assets/javascripts/lib/utils/suppress_ajax_errors_during_navigation.js

@@ -2,8 +2,8 @@
  * An Axios error interceptor that suppresses AJAX errors caused
  * by the request being cancelled when the user navigates to a new page
  */
-export default (err, isUserNavigating, featureFlagEnabled) => {
-  if (featureFlagEnabled && isUserNavigating && err.code === 'ECONNABORTED') {
+export default (err, isUserNavigating) => {
+  if (isUserNavigating && err.code === 'ECONNABORTED') {
     // If the user is navigating away from the current page,
     // prevent .then() and .catch() handlers from being
     // called by returning a Promise that never resolves

lib/gitlab/gon_helper.rb

@@ -41,7 +41,6 @@ module Gitlab
 
       # Initialize gon.features with any flags that should be
       # made globally available to the frontend
-      push_frontend_feature_flag(:suppress_ajax_navigation_errors, default_enabled: true)
       push_frontend_feature_flag(:snippets_vue, default_enabled: false)
     end
 

spec/frontend/lib/utils/suppress_ajax_errors_during_navigation_spec.js

@@ -6,24 +6,20 @@ describe('suppressAjaxErrorsDuringNavigation', () => {
   const NAV_ERR_CODE = 'ECONNABORTED';
 
   it.each`
-    isFeatureFlagEnabled | isUserNavigating | code
-    ${false}             | ${false}         | ${OTHER_ERR_CODE}
-    ${false}             | ${false}         | ${NAV_ERR_CODE}
-    ${false}             | ${true}          | ${OTHER_ERR_CODE}
-    ${false}             | ${true}          | ${NAV_ERR_CODE}
-    ${true}              | ${false}         | ${OTHER_ERR_CODE}
-    ${true}              | ${false}         | ${NAV_ERR_CODE}
-    ${true}              | ${true}          | ${OTHER_ERR_CODE}
-  `('should return a rejected Promise', ({ isFeatureFlagEnabled, isUserNavigating, code }) => {
+    isUserNavigating | code
+    ${false}         | ${OTHER_ERR_CODE}
+    ${false}         | ${NAV_ERR_CODE}
+    ${true}          | ${OTHER_ERR_CODE}
+  `('should return a rejected Promise', ({ isUserNavigating, code }) => {
     const err = { code };
-    const actual = suppressAjaxErrorsDuringNavigation(err, isUserNavigating, isFeatureFlagEnabled);
+    const actual = suppressAjaxErrorsDuringNavigation(err, isUserNavigating);
 
     return expect(actual).rejects.toBe(err);
   });
 
   it('should return a Promise that never resolves', () => {
     const err = { code: NAV_ERR_CODE };
-    const actual = suppressAjaxErrorsDuringNavigation(err, true, true);
+    const actual = suppressAjaxErrorsDuringNavigation(err, true);
 
     const thenCallback = jest.fn();
     const catchCallback = jest.fn();