From 413778662d738964ec7cb38e4b51fb6a4ddaabf9 Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Thu, 8 Dec 2016 15:13:37 +0000
Subject: [PATCH 1/2] Catch synchronous errors from spawning yarn

---
 packages/create-react-app/index.js | 57 +++++++++++++++++-------------
 1 file changed, 33 insertions(+), 24 deletions(-)

diff --git a/packages/create-react-app/index.js b/packages/create-react-app/index.js
index 23d8b5e8de..80faf23bfc 100644
--- a/packages/create-react-app/index.js
+++ b/packages/create-react-app/index.js
@@ -108,38 +108,47 @@ function createApp(name, verbose, version) {
 }
 
 function install(packageToInstall, verbose, callback) {
-  var args = [
-    'add',
-    '--dev',
-    '--exact',
-    packageToInstall,
-  ];
-  var proc = spawn('yarn', args, {stdio: 'inherit'});
-
-  var yarnExists = true;
-  proc.on('error', function (err) {
-    if (err.code === 'ENOENT') {
-      yarnExists = false;
-    }
-  });
-  proc.on('close', function (code) {
-    if (yarnExists) {
-      callback(code, 'yarn', args);
-      return;
-    }
-    // No Yarn installed, continuing with npm.
-    args = [
+  function fallbackToNpm() {
+    var npmArgs = [
       'install',
       verbose && '--verbose',
       '--save-dev',
       '--save-exact',
       packageToInstall,
     ].filter(function(e) { return e; });
-    var npmProc = spawn('npm', args, {stdio: 'inherit'});
+    var npmProc = spawn('npm', npmArgs, {stdio: 'inherit'});
     npmProc.on('close', function (code) {
-      callback(code, 'npm', args);
+      callback(code, 'npm', npmArgs);
     });
-  });
+  }
+
+  var yarnArgs = [
+    'add',
+    '--dev',
+    '--exact',
+    packageToInstall,
+  ];
+  var yarnProc;
+  var yarnExists = true;
+  try {
+    yarnProc = spawn('yarn', yarnArgs, {stdio: 'inherit'});
+    yarnProc.on('error', function (err) {
+      if (err.code === 'ENOENT') {
+        yarnExists = false;
+      }
+    });
+    yarnProc.on('close', function (code) {
+      if (yarnExists) {
+        callback(code, 'yarn', yarnArgs);
+        return;
+      }
+    });
+  } catch (err) {
+    // It's not clear why we end up here in some cases but we need this.
+    // https://github.com/facebookincubator/create-react-app/issues/1200
+    yarnExists = false;
+    fallbackToNpm();
+  }
 }
 
 function run(root, appName, version, verbose, originalDirectory) {

From a87b2796424ceb4d21fdc1e09ff5a0c20bbe9c1d Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Thu, 8 Dec 2016 15:29:04 +0000
Subject: [PATCH 2/2] Fix issues

---
 packages/create-react-app/index.js | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/packages/create-react-app/index.js b/packages/create-react-app/index.js
index 80faf23bfc..403e89edfe 100644
--- a/packages/create-react-app/index.js
+++ b/packages/create-react-app/index.js
@@ -132,23 +132,25 @@ function install(packageToInstall, verbose, callback) {
   var yarnExists = true;
   try {
     yarnProc = spawn('yarn', yarnArgs, {stdio: 'inherit'});
-    yarnProc.on('error', function (err) {
-      if (err.code === 'ENOENT') {
-        yarnExists = false;
-      }
-    });
-    yarnProc.on('close', function (code) {
-      if (yarnExists) {
-        callback(code, 'yarn', yarnArgs);
-        return;
-      }
-    });
   } catch (err) {
     // It's not clear why we end up here in some cases but we need this.
     // https://github.com/facebookincubator/create-react-app/issues/1200
     yarnExists = false;
     fallbackToNpm();
+    return;
   }
+  yarnProc.on('error', function (err) {
+    if (err.code === 'ENOENT') {
+      yarnExists = false;
+    }
+  });
+  yarnProc.on('close', function (code) {
+    if (yarnExists) {
+      callback(code, 'yarn', yarnArgs);
+    } else {
+      fallbackToNpm();
+    }
+  });
 }
 
 function run(root, appName, version, verbose, originalDirectory) {