add set up slackLegacy in index.js

src/server/crowi/index.js

@@ -105,6 +105,7 @@ Crowi.prototype.init = async function() {
     this.setupSearcher(),
     this.setupMailer(),
     this.setupSlack(),
+    this.setupSlackLegacy(),
     this.setupCsrf(),
     this.setUpFileUpload(),
     this.setUpFileUploaderSwitchService(),
@@ -385,6 +386,15 @@ Crowi.prototype.setupSlack = async function() {
   }));
 };
 
+Crowi.prototype.setupSlackLegacy = async function() {
+  const self = this;
+
+  return new Promise(((resolve, reject) => {
+    self.slackLegacy = require('../util/slack-legacy')(self);
+    resolve();
+  }));
+};
+
 Crowi.prototype.setupCsrf = async function() {
   const Tokens = require('csrf');
   this.tokens = new Tokens();