Why am I getting this error when I run localhost?

Error: C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\views\navbar.pug:17:81
    15|         if currentUser
    16|             div
  > 17|                 img.avatar.img-circle.hidden-xs-down(src='/images/avatar.png', alt='avatar')        
----------------------------------------------------------------------------------------^
    18|                 a.btn.btn-light.pull-md-right(href='/logout') Log out
    19|             else
    20|                 a.btn.btn-info.pull-md-right(href='login') Login

unexpected text "       
        "
    at makeError (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-error\index.js:32:13)
    at Lexer.error (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-lexer\index.js:58:15)
    at Lexer.fail (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-lexer\index.js:1301:10)
    at Lexer.advance (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-lexer\index.js:1361:15)
    at Lexer.callLexerFunction (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-lexer\index.js:1316:23)
    at Lexer.getTokens (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-lexer\index.js:1372:12)
    at lex (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-lexer\index.js:12:42)
    at Object.lex (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug\lib\index.js:99:27)
    at Function.loadString [as string] (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-load\index.js:44:24)
    at C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-load\index.js:31:27
    at walkAST (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-walk\index.js:23:18)
    at C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-walk\index.js:104:20
    at Array.reduce (native)
    at walkAndMergeNodes (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-walk\index.js:103:18)
    at walkAST (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-walk\index.js:37:19)
    at walkAST (C:\Users\Rusie\Documents\susan_treehouse\User_Authentication_with_Express_and_Mongo\Using_Session_Variables_to_Customize_Content\S3V5\node_modules\pug-walk\index

nav.navbar.navbar-fixed-top.navbar-dark.bg-inverse
        button.navbar-toggler.hidden-md-up.pull-xs-right(type='button', data-toggle='collapse', data-target='#navbar') ☰
        #navbar.navbar-nav.collapse.navbar-toggleable-sm
            .container
                a.navbar-brand(href='/')
                    i.icn-logo.material-icons bookmark_border
                    | Bookworm
        .nav-items.clearfix
            if !currentUser
                a.nav-item.nav-link(href='register') Sign Up
        a.nav-item.nav-link(href='about') About
        a.nav-item.nav-link(href='contact') Contact
        a.nav-item.nav-link(href='profile') My Profile

        if currentUser
            div
                img.avatar.img-circle.hidden-xs-down(src='/images/avatar.png', alt='avatar')        
                a.btn.btn-light.pull-md-right(href='/logout') Log out
            else
                a.btn.btn-info.pull-md-right(href='login') Login

var express = require('express');
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
var session = require('express-session');
var app = express();

// use sessions for tracking logins
app.use(session({
  secret: 'treehouse loves you',
  resave: true,
  saveUninitialized: false
}));

// make user ID available in templates
app.use(function (req, res, next) {
    res.locals.currentUser = req.session.userID;
    next();
});

// mongodb connection
mongoose.connect("mongodb://localhost:27017/bookworm");
var db = mongoose.connection;
// mongo error
db.on('error', console.error.bind(console, 'connection error:'));

// parse incoming requests
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

// serve static files from /public
app.use(express.static(__dirname + '/public'));

// view engine setup
app.set('view engine', 'pug');
app.set('views', __dirname + '/views');

// include routes
var routes = require('./routes/index');
app.use('/', routes);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('File Not Found');
  err.status = 404;
  next(err);
});

// error handler
// define as the last app.use callback
app.use(function(err, req, res, next) {
  res.status(err.status || 500);
  res.render('error', {
    message: err.message,
    error: {}
  });