Add explicit file not found checking, thanks @RubenVerborgh

Author: kjetilk

lib/acl-checker.js

@@ -54,7 +54,7 @@ class ACLChecker {
     const nearestACL = this.getPossibleACLs().reduce((prevACL, acl) => {
       return prevACL.catch(() => new Promise((resolve, reject) => {
         this.fetch(acl, (err, graph) => {
-          if (err || !graph || !graph.length) {
+          if (err && err.code !== 'ENOENT' || !graph || !graph.length) {
             isContainer = true
             reject(err)
           } else {