chore: add strict mode (#2974)

src/rest/APIRequest.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const querystring = require('querystring');
 const FormData = require('form-data');
 const https = require('https');

src/rest/APIRouter.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const noop = () => {}; // eslint-disable-line no-empty-function
 const methods = ['get', 'post', 'delete', 'patch', 'put'];
 const reflectors = [

src/rest/DiscordAPIError.js

@@ -1,3 +1,5 @@
+'use strict';
+
 /**
  * Represents an error from the Discord API.
  * @extends Error

src/rest/HTTPError.js

@@ -1,3 +1,5 @@
+'use strict';
+
 /**
  * Represents a HTTP error from a request.
  * @extends Error

src/rest/RESTManager.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const RequestHandler = require('./RequestHandler');
 const APIRequest = require('./APIRequest');
 const routeBuilder = require('./APIRouter');

src/rest/RequestHandler.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const DiscordAPIError = require('./DiscordAPIError');
 const HTTPError = require('./HTTPError');
 const Util = require('../util/Util');