diff --git a/assets/javascripts/discourse/controllers/docs-index.js b/assets/javascripts/discourse/controllers/docs-index.js
index edf89a3..877abd8 100644
--- a/assets/javascripts/discourse/controllers/docs-index.js
+++ b/assets/javascripts/discourse/controllers/docs-index.js
@@ -229,10 +229,10 @@ export default Controller.extend({
       return [];
     }
 
-    return this.siteSettings.docs_categories.split("|").map((c) => {
-      const id = parseInt(c, 10);
-      return this.site.categories.findBy("id", id).name;
-    });
+    return this.siteSettings.docs_categories
+      .split("|")
+      .map((c) => this.site.categories.findBy("id", parseInt(c, 10))?.name)
+      .filter(Boolean);
   },
 
   @discourseComputed()
diff --git a/test/javascripts/unit/controllers/docs-index-test.js b/test/javascripts/unit/controllers/docs-index-test.js
new file mode 100644
index 0000000..fc36b39
--- /dev/null
+++ b/test/javascripts/unit/controllers/docs-index-test.js
@@ -0,0 +1,15 @@
+import { module, test } from "qunit";
+import { setupTest } from "ember-qunit";
+import { getOwner } from "discourse-common/lib/get-owner";
+
+module("Unit | Controller | docs-index", function (hooks) {
+  setupTest(hooks);
+
+  test("docsCategories ignores invalid category ids", function (assert) {
+    const siteSettings = getOwner(this).lookup("service:site-settings");
+    siteSettings.docs_categories = "1|2|3|333|999";
+
+    const controller = getOwner(this).lookup("controller:docs-index");
+    assert.deepEqual(controller.docsCategories, ["bug", "feature", "meta"]);
+  });
+});