Creo qué es por esto:
angular.js:14642 TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at chat.js?v=31.3:1953
    at angular.js:17000
    at m.$digest (angular.js:18182)
    at m.$apply (angular.js:18480)
    at l (angular.js:12501)
    at XMLHttpRequest.s.onload (angular.js:12655) "Possibly unhandled rejection: {}"