From 11e05e131b4f2af8c18472a067de481bac9586ad Mon Sep 17 00:00:00 2001
From: Ben Heidemann <ben@heidemann.co.uk>
Date: Sun, 18 Apr 2021 15:42:47 +0100
Subject: [PATCH] fix: make fs proxy return undefined for keys which do not
 exist on the file system instance

---
 shims/fs.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/shims/fs.js b/shims/fs.js
index d60986f..d3b259d 100644
--- a/shims/fs.js
+++ b/shims/fs.js
@@ -26,8 +26,16 @@ var fsInstance = new FileSystem({ provider }, (err) => {
   }
 });
 
+function proxyHasProp(target, prop) {
+  return prop in target;
+}
+
 const fsPromises = new Proxy(fsInstance.promises, {
   get(target, prop) {
+    if (!proxyHasProp(target, prop)) {
+      return;
+    }
+
     return async (...args) => {
       await fsReady;
       return await target[prop](...args);
@@ -37,6 +45,10 @@ const fsPromises = new Proxy(fsInstance.promises, {
 
 const fs = new Proxy(fsInstance, {
   get(target, prop) {
+    if (!proxyHasProp(target, prop)) {
+      return;
+    }
+
     if (prop === 'promises') {
       return fsPromises;
     }