FIX: Ensure 'untagged' document title is set correctly (#24689)

https://meta.discourse.org/t/286130/4

app/assets/javascripts/discourse/app/routes/tag-show.js

@@ -173,7 +173,8 @@ export default class TagShowRoute extends DiscourseRoute {
     );
     const model = this.currentModel;
 
-    if (model?.tag?.id) {
+    const tag = model?.tag?.id;
+    if (tag && tag !== NONE) {
       if (model.category) {
         return I18n.t("tagging.filters.with_category", {
           filter: filterText,

app/assets/javascripts/discourse/tests/acceptance/tags-test.js

@@ -10,6 +10,7 @@ import {
   updateCurrentUser,
 } from "discourse/tests/helpers/qunit-helpers";
 import selectKit from "discourse/tests/helpers/select-kit-helper";
+import I18n from "discourse-i18n";
 
 acceptance("Tags", function (needs) {
   needs.user();
@@ -310,6 +311,21 @@ acceptance("Tag info", function (needs) {
       });
     });
 
+    server.get("/tags/c/feature/2/none/l/latest.json", () => {
+      return helper.response({
+        users: [],
+        primary_groups: [],
+        topic_list: {
+          can_create_topic: true,
+          draft: null,
+          draft_key: "new_topic",
+          draft_sequence: 1,
+          per_page: 30,
+          topics: [],
+        },
+      });
+    });
+
     server.get("/tag/planters/info", () => {
       return helper.response({
         __rest_serializer: "1",
@@ -509,6 +525,40 @@ acceptance("Tag info", function (needs) {
     assert.strictEqual(currentURL(), "/tags/c/feature/2/none/planters");
   });
 
+  test("sets document title correctly", async function (assert) {
+    await visit("/tag/planters");
+    assert.strictEqual(
+      document.title,
+      I18n.t("tagging.filters.without_category", {
+        filter: "Latest",
+        tag: "planters",
+      }) + ` - ${this.siteSettings.title}`
+    );
+
+    await click(".category-breadcrumb .category-drop-header");
+    await click(`.category-breadcrumb .category-row[data-name="feature"]`);
+    assert.strictEqual(currentURL(), "/tags/c/feature/2/planters");
+    assert.strictEqual(
+      document.title,
+      I18n.t("tagging.filters.with_category", {
+        filter: "Latest",
+        tag: "planters",
+        category: "feature",
+      }) + ` - ${this.siteSettings.title}`
+    );
+
+    await click(".tag-drop-header");
+    await click(`.tag-row[data-value="no-tags"]`);
+    assert.strictEqual(currentURL(), "/tags/c/feature/2/none");
+    assert.strictEqual(
+      document.title,
+      I18n.t("tagging.filters.untagged_with_category", {
+        filter: "Latest",
+        category: "feature",
+      }) + ` - ${this.siteSettings.title}`
+    );
+  });
+
   test("can visit show-category-latest routes", async function (assert) {
     await visit("/tags/c/feature/2/planters");