Add lint for unused locals (#8007)

src/PasswordReset.ts

@@ -1,6 +1,6 @@
 /*
 Copyright 2015, 2016 OpenMarket Ltd
-Copyright 2019 The Matrix.org Foundation C.I.C.
+Copyright 2019 - 2022 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -29,7 +29,6 @@ import { _t } from './languageHandler';
 export default class PasswordReset {
     private client: MatrixClient;
     private clientSecret: string;
-    private identityServerDomain: string;
     private password: string;
     private sessionId: string;
 
@@ -44,7 +43,6 @@ export default class PasswordReset {
             idBaseUrl: identityUrl,
         });
         this.clientSecret = this.client.generateClientSecret();
-        this.identityServerDomain = identityUrl ? identityUrl.split("://")[1] : null;
     }
 
     /**