From 622e87c196c67cebef33750adf6527b79bdc930c Mon Sep 17 00:00:00 2001
From: Kingdaro <kingdaro@gmail.com>
Date: Sat, 10 Sep 2016 16:18:21 -0400
Subject: [PATCH 1/3] add undefined check for instance methods

---
 src/core/instance/state.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/core/instance/state.js b/src/core/instance/state.js
index b6a104f0170..79d09353f18 100644
--- a/src/core/instance/state.js
+++ b/src/core/instance/state.js
@@ -142,7 +142,9 @@ function initMethods (vm: Component) {
   const methods = vm.$options.methods
   if (methods) {
     for (const key in methods) {
-      vm[key] = bind(methods[key], vm)
+      if (methods[key] != null) {
+        vm[key] = bind(methods[key], vm)
+      }
     }
   }
 }

From 3cb17d419788cef84d3c800f12c368e83c79bc5b Mon Sep 17 00:00:00 2001
From: Kingdaro <kingdaro@gmail.com>
Date: Sat, 10 Sep 2016 16:22:34 -0400
Subject: [PATCH 2/3] added a warning for undefined methods

---
 src/core/instance/state.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/core/instance/state.js b/src/core/instance/state.js
index 79d09353f18..1ba5044927a 100644
--- a/src/core/instance/state.js
+++ b/src/core/instance/state.js
@@ -144,6 +144,8 @@ function initMethods (vm: Component) {
     for (const key in methods) {
       if (methods[key] != null) {
         vm[key] = bind(methods[key], vm)
+      } else {
+        warn(`The method ${key} on vue instance is undefined.`, vm)
       }
     }
   }

From 236fdc30c79dd4d35b755e353bf2a586a494dd09 Mon Sep 17 00:00:00 2001
From: Darius Tall <kingdaro@gmail.com>
Date: Sun, 11 Sep 2016 09:14:25 -0400
Subject: [PATCH 3/3] add production ENV check

---
 src/core/instance/state.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/instance/state.js b/src/core/instance/state.js
index 1ba5044927a..8a7545f9bd9 100644
--- a/src/core/instance/state.js
+++ b/src/core/instance/state.js
@@ -144,7 +144,7 @@ function initMethods (vm: Component) {
     for (const key in methods) {
       if (methods[key] != null) {
         vm[key] = bind(methods[key], vm)
-      } else {
+      } else if (process.env.NODE_ENV !== 'production') {
         warn(`The method ${key} on vue instance is undefined.`, vm)
       }
     }