use underscore.each so it doesn’t blow up on non array.

services/web/app/coffee/Features/References/ReferencesHandler.coffee

@@ -4,7 +4,7 @@ settings = require("settings-sharelatex")
 ProjectGetter = require "../Project/ProjectGetter"
 UserGetter = require "../User/UserGetter"
 DocumentUpdaterHandler = require('../DocumentUpdater/DocumentUpdaterHandler')
-U = require('underscore')
+_ = require('underscore')
 Async = require('async')
 
 oneMinInMs = 60 * 1000
@@ -22,24 +22,24 @@ module.exports = ReferencesHandler =
 	_findBibFileIds: (project) ->
 		ids = []
 		_process = (folder) ->
-			(folder.fileRefs or []).forEach (file) ->
+			_.each (folder.fileRefs or []), (file) ->
 				if file?.name?.match(/^.*\.bib$/)
 					ids.push(file._id)
-			(folder.folders or []).forEach (folder) ->
+			_.each (folder.folders or []), (folder) ->
 				_process(folder)
-		(project.rootFolder or []).forEach (rootFolder) ->
+		_.each (project.rootFolder or []), (rootFolder) ->
 			_process(rootFolder)
 		return ids
 
 	_findBibDocIds: (project) ->
 		ids = []
 		_process = (folder) ->
-			(folder.docs or []).forEach (doc) ->
+			_.each (folder.docs or []), (doc) ->
 				if doc?.name?.match(/^.*\.bib$/)
 					ids.push(doc._id)
-			(folder.folders or []).forEach (folder) ->
+			_.each (folder.folders or []), (folder) ->
 				_process(folder)
-		(project.rootFolder or []).forEach (rootFolder) ->
+		_.each (project.rootFolder or []), (rootFolder) ->
 			_process(rootFolder)
 		return ids
 

services/web/test/UnitTests/coffee/References/ReferencesHandlerTests.coffee

@@ -322,6 +322,11 @@ describe 'ReferencesHandler', ->
 			result = @handler._findBibDocIds(@fakeProject)
 			expect(result).to.deep.equal @expectedIds
 
+		it 'should not error with a non array of folders from dirty data', ->
+			@fakeProject.rootFolder[0].folders[0].folders = {}
+			result = @handler._findBibDocIds(@fakeProject)
+			expect(result).to.deep.equal @expectedIds
+
 	describe '_findBibFileIds', ->
 
 		beforeEach ->