From 1d6fadd7724819a26eea60c8b47cc26a7bc989ca Mon Sep 17 00:00:00 2001
From: Wesley de Souza <souza@work.co>
Date: Thu, 25 May 2017 15:41:05 -0400
Subject: [PATCH] Prevent `this.setState` if there is no component

On `_handleDoneLeaving`, prevent calling `setState` if the component is unmounted.

This was triggering this error:

> Warning: setState(...): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op. Please check the code for the ReactTransitionGroup component.
---
 index.js               | 2 +-
 src/TransitionGroup.js | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index bf4045fa..3666b25f 100644
--- a/index.js
+++ b/index.js
@@ -437,7 +437,7 @@ var TransitionGroup = function (_React$Component) {
       if (currentChildMapping && currentChildMapping.hasOwnProperty(key)) {
         // This entered again before it fully left. Add it again.
         _this.performEnter(key);
-      } else {
+      } else if (component) {
         _this.setState(function (state) {
           var newChildren = Object.assign({}, state.children);
           delete newChildren[key];
diff --git a/src/TransitionGroup.js b/src/TransitionGroup.js
index 2cba6a6a..726b3fed 100644
--- a/src/TransitionGroup.js
+++ b/src/TransitionGroup.js
@@ -174,7 +174,7 @@ class TransitionGroup extends React.Component {
     if (currentChildMapping && currentChildMapping.hasOwnProperty(key)) {
       // This entered again before it fully left. Add it again.
       this.performEnter(key);
-    } else {
+    } else if (component) {
       this.setState((state) => {
         let newChildren = Object.assign({}, state.children);
         delete newChildren[key];