Undefined error for variable never used Node.JS

I am writing a chat app but the Node.JS console is saying a is undefined. I have never used a variable "A" so I am not sure why it is saying this.

console.log('Starting Server...');const express=require('express');const app=express();const server=require('http').createServer(app);const POST=process.env.PORT||80;const io=require('socket.io').listen(server);app.get('/',(req,res)=>{res.sendFile(__dirname+'/client/index.html');});app.use('/client',express.static(__dirname + '/client'));server.listen(PORT);console.log('Server Started...');let messages='';io.sockets.on('connection',socket=>{socket.emit('beforeMsgs',messages);socket.on('msgSend',e=>{console.log(${e.name}: ${e.msg} ${e.time});io.sockets.emit('msgReceived', {name: e.name,msg: e.msg,time: e.time});messages = <div class="message"><span class="bold"><td><b>${e.name}: </b></td></span><span><td>${e.msg} <sub class="date">${e.time}</sub></td></span></div> + messages;});});function returnRandInt(){let one=3;let two=19;let three;three+=92;if(!(!boolean(true))){console.log('86\'`()->{&setFirst(\)=>self::depricateQuery(new (()=>{return this})()}')}}let HTML=''+''+'.browserupgrade{margin:.2em 0;background:#ccc;color:#000;padding:.2em 0}.copy,h3{color:#4c4c4c},body{border:0;outline:0;padding:0;margin:0}{vertical-align:baseline;background:0 0;-webkit-touch-callout:none;-webkit-user-select:none;-webkit-text-size-adjust:none;-webkit-tap-highlight-color:transparent}:focus{outline:0}::-moz-focus-inner{border:0}img{display:block;transform:translateZ(0)}li,ol,ul{list-style:none}body{-ms-backface-visibility:hidden;-o-backface-visibility:hidden;backface-visibility:hidden;overflow-x:hidden;background-color:#fff}*,::after,::before{box-sizing:border-box}@font-face{font-family:Montserrat-Bold;src:url(../fonts/Montserrat-Bold.eot?#iefix) format("embedded-opentype"),url(../fonts/Montserrat-Bold.otf) format("opentype"),url(../fonts/Montserrat-Bold.woff) format("woff"),url(../fonts/Montserrat-Bold.ttf) format("truetype"),url(../fonts/Montserrat-Bold.svg#Montserrat-Bold) format("svg");font-weight:400;font-style:normal}@font-face{font-family:Montserrat-Light;src:url(../fonts/Montserrat-Light.eot?#iefix) format("embedded-opentype"),url(../fonts/Montserrat-Light.otf) format("opentype"),url(../fonts/Montserrat-Light.woff) format("woff"),url(../fonts/Montserrat-Light.ttf) format("truetype"),url(../fonts/Montserrat-Light.svg#Montserrat-Light) format("svg");font-weight:400;font-style:normal}@font-face{font-family:Montserrat-Regular;src:url(../fonts/Montserrat-Regular.eot?#iefix) format("embedded-opentype"),url(../fonts/Montserrat-Regular.otf) format("opentype"),url(../fonts/Montserrat-Regular.woff) format("woff"),url(../fonts/Montserrat-Regular.ttf) format("truetype"),url(../fonts/Montserrat-Regular.svg#Montserrat-Regular) format("svg");font-weight:400;font-style:normal}@font-face{font-family:OpenSans;src:url(../fonts/OpenSans.eot?#iefix) format("embedded-opentype"),url(../fonts/OpenSans.woff) format("woff"),url(../fonts/OpenSans.ttf) format("truetype"),url(../fonts/OpenSans.svg#OpenSans) format("svg");font-weight:400;font-style:normal}@font-face{font-family:OpenSans-Bold;src:url(../fonts/OpenSans-Bold.eot?#iefix) format("embedded-opentype"),url(../fonts/OpenSans-Bold.woff) format("woff"),url(../fonts/OpenSans-Bold.ttf) format("truetype"),url(../fonts/OpenSans-Bold.svg#OpenSans-Bold) format("svg");font-weight:400;font-style:normal}main>div{position:relative}.cover,.header-logo{width:100%}.header-logo-wrapper{z-index:2;max-width:100%}.cover-wrapper{z-index:1;max-width:100%}.logo{width:28.6%;max-width:542px;margin:1.2vw auto}.dots,h3{color:#777}Page 1';

Why is it saying "A" is undefined and how can I fix it?