return 404 on project details not found

services/web/app/coffee/Features/Project/ProjectApiController.coffee

@@ -1,4 +1,5 @@
 ProjectDetailsHandler = require("./ProjectDetailsHandler")
+Errors = require("../Errors/Errors")
 logger = require("logger-sharelatex")
 
 
@@ -7,8 +8,11 @@ module.exports =
 	getProjectDetails : (req, res)->
 		{project_id} = req.params
 		ProjectDetailsHandler.getDetails project_id, (err, projDetails)->
-			if err?
+			if err? and err instanceof Errors.NotFoundError
+				return res.sendStatus 404
+			else if err?
 				logger.log err:err, project_id:project_id, "something went wrong getting project details"
 				return res.sendStatus 500
-			res.json(projDetails)
+			else
+				res.json(projDetails)