js_error_message window.livePortiaPage.sendEvent

2017-03-09 07:35:15.262205 [_GenericHTTPChannelProtocol,0,127.0.0.1] u'Websocket Closed: id= t=0 user=defaultuser command='
2017-03-09 07:35:15.268232 [-] "127.0.0.1" - - [09/Mar/2017:07:35:14 +0000] "GET / HTTP/1.0" 200 1992 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36"
[09/Mar/2017 07:35:15] "GET /api/projects HTTP/1.0" 200 1813
[09/Mar/2017 07:35:15] "GET /server_capabilities HTTP/1.0" 200 207
[09/Mar/2017 07:35:16] "GET /api/projects/ruby-china/spiders HTTP/1.0" 200 81
[09/Mar/2017 07:35:16] "GET /api/projects/ruby-china/schemas HTTP/1.0" 200 81
[09/Mar/2017 07:35:16] "GET /api/projects/ruby-china HTTP/1.0" 200 654
2017-03-09 07:35:16.517012 [-] {'js_error_type': u'TypeError', 'js_error': u"TypeError: undefined is not an object (evaluating 'window.livePortiaPage.sendEvent')", 'type': 'JS_ERROR', 'message': 'JS error: u"TypeError: undefined is not an object (evaluating \'window.livePortiaPage.sendEvent\')"', 'js_error_message': u"undefined is not an object (evaluating 'window.livePortiaPage.sendEvent')"}
[09/Mar/2017 07:35:27] "POST /api/projects/ruby-china/spiders HTTP/1.0" 201 997
[09/Mar/2017 07:35:27] "GET /api/projects/ruby-china/spiders/ruby-china HTTP/1.0" 200 1067
[09/Mar/2017 07:35:27] "GET /api/projects/ruby-china/spiders/ruby-china/samples HTTP/1.0" 200 100
how can i solve it?
scrapinghub / portia

js_error_message window.livePortiaPage.sendEvent #755
