fix: Signup on matrix.org

lib/pages/signup.dart

@@ -101,7 +101,9 @@ class SignupPageController extends State<SignupPage> {
     } catch (e) {
       error = (e as Object).toLocalizedString(context);
     } finally {
-      setState(() => loading = false);
+      if (mounted) {
+        setState(() => loading = false);
+      }
     }
   }
 

lib/pages/views/homeserver_picker_view.dart

@@ -141,10 +141,7 @@ class HomeserverPickerView extends StatelessWidget {
                                     labelText: L10n.of(context).login,
                                   ),
                                 ),
-                              if (controller.registrationSupported &&
-                                  // Registration is broken on matrix.org
-                                  Matrix.of(context).client.homeserver.host !=
-                                      'matrix-client.matrix.org')
+                              if (controller.registrationSupported)
                                 Center(
                                   child: _LoginButton(
                                     onPressed: controller.signUpAction,