FIX: Bookmark list showing wrong no content message (#10501)

Meta report: https://meta.discourse.org/t/spurious-permissions-error-after-deleting-last-bookmark/161289

When deleting all bookmarks in their list, users were seeing an "access denied" message instead of the regular no content message. This is because when we were calling loadMore and no further results were returned, we were presuming the null response from the resolved promise meant that there was a permissions error. Fixed this and moved the message into a computed property to show the correct message.

app/assets/javascripts/discourse/app/controllers/user-activity-bookmarks.js

@@ -41,9 +41,20 @@ export default Controller.extend({
       });
   },
 
-  @discourseComputed("loaded", "content.length", "noResultsHelp")
-  noContent(loaded, contentLength, noResultsHelp) {
-    return loaded && contentLength === 0 && noResultsHelp;
+  @discourseComputed("loaded", "content.length")
+  noContent(loaded, contentLength) {
+    return loaded && contentLength === 0;
+  },
+
+  @discourseComputed("noResultsHelp", "noContent")
+  noResultsHelpMessage(noResultsHelp, noContent) {
+    if (noResultsHelp) {
+      return noResultsHelp;
+    }
+    if (noContent) {
+      return I18n.t("bookmarks.no_user_bookmarks");
+    }
+    return "";
   },
 
   @action
@@ -78,7 +89,6 @@ export default Controller.extend({
 
   _processLoadResponse(response) {
     if (!response) {
-      this._bookmarksListDenied();
       return;
     }
 

app/assets/javascripts/discourse/app/templates/user/bookmarks.hbs

@@ -11,7 +11,7 @@
       icon="search"}}
 </div>
 {{#if noContent}}
-  <div class="alert alert-info">{{noResultsHelp}}</div>
+  <div class="alert alert-info">{{noResultsHelpMessage}}</div>
 {{else}}
   {{bookmark-list
     loadMore=(action "loadMore")

config/locales/client.en.yml

@@ -303,6 +303,7 @@ en:
       no_timezone: 'You have not set a timezone yet. You will not be able to set reminders. Set one up <a href="%{basePath}/my/preferences/profile">in your profile</a>.'
       invalid_custom_datetime: "The date and time you provided is invalid, please try again."
       list_permission_denied: "You do not have permission to view this user's bookmarks."
+      no_user_bookmarks: "You have no bookmarked posts; bookmarks allow you to quickly refer to specific posts."
       auto_delete_preference:
         label: "Automatically delete"
         never: "Never"