Merge pull request #570 from sharelatex/ho-null-check-redis-sessions

Ho null check redis sessions

services/web/app/coffee/Features/User/UserController.coffee

@@ -120,8 +120,9 @@ module.exports = UserController =
 		req.session.destroy (err)->
 			if err
 				logger.err err: err, 'error destorying session'
-			UserSessionsManager.untrackSession(user, sessionId)
-			SudoModeHandler.clearSudoMode(user._id)
+			if user?
+				UserSessionsManager.untrackSession(user, sessionId)
+				SudoModeHandler.clearSudoMode(user._id)
 			res.redirect '/login'
 
 	register : (req, res, next = (error) ->)->

services/web/app/coffee/Features/User/UserSessionsManager.coffee

@@ -114,7 +114,7 @@ module.exports = UserSessionsManager =
 					callback(null)
 
 	touch: (user, callback=(err)->) ->
-		if !user
+		if !user?
 			logger.log {}, "no user to touch sessions for, returning"
 			return callback(null)
 		sessionSetKey = UserSessionsRedis.sessionSetKey(user)
@@ -125,7 +125,7 @@ module.exports = UserSessionsManager =
 			callback(null)
 
 	_checkSessions: (user, callback=(err)->) ->
-		if !user
+		if !user?
 			logger.log {}, "no user, returning"
 			return callback(null)
 		logger.log {user_id: user._id}, "checking sessions for user"