Merge commit '00c222377db0e305ac3f4a15bf1c18eb89c1f45f' into glitch-soc/merge-upstream

Conflicts:
- `.rubocop_todo.yml`:
  Took upstream's changes.

app/javascript/mastodon/features/interaction_modal/index.jsx

@@ -13,7 +13,7 @@ import { registrationsOpen } from 'mastodon/initial_state';
 
 const mapStateToProps = (state, { accountId }) => ({
   displayNameHtml: state.getIn(['accounts', accountId, 'display_name_html']),
-  signupUrl: state.getIn(['server', 'server', 'registrations', 'url'], '/auth/sign_up'),
+  signupUrl: state.getIn(['server', 'server', 'registrations', 'url'], null) || '/auth/sign_up',
 });
 
 const mapDispatchToProps = (dispatch) => ({

app/javascript/mastodon/features/status/index.jsx

@@ -166,8 +166,9 @@ const makeMapStateToProps = () => {
 };
 
 const truncate = (str, num) => {
-  if (str.length > num) {
-    return str.slice(0, num) + '…';
+  const arr = Array.from(str);
+  if (arr.length > num) {
+    return arr.slice(0, num).join('') + '…';
   } else {
     return str;
   }

app/javascript/mastodon/features/ui/components/sign_in_banner.jsx

@@ -17,7 +17,7 @@ const SignInBanner = () => {
 
   let signupButton;
 
-  const signupUrl = useAppSelector((state) => state.getIn(['server', 'server', 'registrations', 'url'], '/auth/sign_up'));
+  const signupUrl = useAppSelector((state) => state.getIn(['server', 'server', 'registrations', 'url'], null) || '/auth/sign_up');
 
   if (registrationsOpen) {
     signupButton = (