From d2407c73fb61aea3b06707a231abc57efbc1b099 Mon Sep 17 00:00:00 2001
From: Swaroop SM <swaroop@cybrilla.com>
Date: Tue, 1 Mar 2016 23:44:01 +0530
Subject: [PATCH] Warn if the included mixin is undefined

---
 src/isomorphic/classic/class/ReactClass.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/isomorphic/classic/class/ReactClass.js b/src/isomorphic/classic/class/ReactClass.js
index 223e58bf63187..9f123661e197f 100644
--- a/src/isomorphic/classic/class/ReactClass.js
+++ b/src/isomorphic/classic/class/ReactClass.js
@@ -437,6 +437,12 @@ function validateMethodOverride(isAlreadyDefined, name) {
  */
 function mixSpecIntoComponent(Constructor, spec) {
   if (!spec) {
+    warning(
+      typeof spec === 'undefined',
+      '%s: You\'re attempting to ' +
+      'include a mixin that is undefined.',
+      Constructor.displayName || 'ReactClass'
+    );
     return;
   }