Failure jade with json - Cannot read property 'length' of undefined - I can't find what's wrong

I'm working on a project, in Node.js, express module, jade files, MongoDB-Mongoose and more.. I've a problem to implement json details from the database to the jade page.

I tried to figure out the problem, unsuccessfully. I would like someone to help me find and fix it. Thanks.

That's the Error message:

TypeError: /Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/views/index.jade:66
   64|   div(id="archive-rooms-container" class="row panel thumbnail-row")
   65|     h4= 'Musical Projects'
 > 66|     each project, index in projects
   67|           div(class='col-md-3 rowSpace')
   68|               ul(class="room-details")
   69|                   li

Cannot read property 'length' of undefined
   at jade_debug.unshift.lineno (eval at <anonymous> (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/jade/lib/jade.js:174:8), <anonymous>:618:31)
   at eval (eval at <anonymous> (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/jade/lib/jade.js:174:8), <anonymous>:815:4)
   at eval (eval at <anonymous> (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/jade/lib/jade.js:174:8), <anonymous>:955:22)
   at res (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/jade/lib/jade.js:175:38)
   at Object.exports.render (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/jade/lib/jade.js:300:10)
   at Object.exports.renderFile (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/jade/lib/jade.js:336:18)
   at View.exports.renderFile [as engine] (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/jade/lib/jade.js:321:21)
   at View.render (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/express/lib/view.js:93:8)
   at EventEmitter.app.render (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/express/lib/application.js:530:10)
   at ServerResponse.res.render (/Users/itzhak/Desktop/Development/Porvivo/AWSporvivo/node_modules/express/lib/response.js:933:7)

Jade code:

each project, index in projects
      div(class='col-md-3 rowSpace')
          ul(class="room-details")
              li
                  a(href="/projects/" + project.sessionId id=project.sessionId)
                      h3(style='margin:0 0 3px')= project.projectName
              - var playerNames = [];
              - for(var playerIndex in project.players) playerNames.push(room.players[playerIndex].name);
              li
                  for playerName in playerNames
                      a(href="../" + playerName)= playerName
          a(href="/projects/" + project.sessionId id=project.sessionId): img(src=project.img class="img-responsive")

Js code (on client side):

function loadProjects() {
    $.getJSON('/projects/info', function( data ) {
        console.log(JSON.stringify(data));
    });
}
$( document ).ready(function() {
    loadProjects();
    setInterval(loadProjects, 10000);
});

app code: (node.js)

var express = require('express'),
router = express.Router(),
Project = require('../schemas/project'),
projects = [];

Project.find().lean().exec(function(err, items) {
        if (err) {
            console.log('* ERROR!!! : ' + err);
        } else {
            projects = items;
            console.log('* SUCCESS : ' + JSON.stringify(projects));
        }
    });

    router.get('/info', function(req, res) {
        res.json({projects: projects});
    });

module.exports = router;

Thanks a lot!

Itzhak.