getting error while clicking on preview button

[nitingarg81]

C:\kendo\kendo-bootstrapper-0.5\lib\project.js:867
for (var i = proj.files.length; --i >= 0;) {
^
TypeError: Cannot read property 'files' of undefined
at get_file_by_name (C:\kendo\kendo-bootstrapper-0.5\lib\project.js:
867:22)
at Object.load_assets (C:\kendo\kendo-bootstrapper-0.5\lib\project.j
s:901:12)
at C:\kendo\kendo-bootstrapper-0.5\bin\start.js:60:34
at Server. (C:\kendo\kendo-bootstrapper-0.5\bin\start.js:
138:32)
at Server.emit (events.js:98:17)
at HTTPParser.parser.onIncoming (http.js:2108:12)
at HTTPParser.parserOnHeadersComplete as onHeadersComplete
at Socket.socket.ondata (http.js:1966:22)
at TCP.onread (net.js:527:27)