move lifecycle check into replaceProps instead of updateComponent

src/core/ReactComponent.js

@@ -278,6 +278,10 @@ var ReactComponent = {
         '`render` method to pass the correct value as props to the component ' +
         'where it is created.'
       );
+      invariant(
+        this.isMounted(),
+        'replaceProps(...): Can only update a mounted component.'
+      );
       this._pendingProps = props;
       ReactUpdates.enqueueUpdate(this, callback);
     },

src/core/ReactCompositeComponent.js

@@ -726,11 +726,6 @@ var ReactCompositeComponentMixin = {
       ReactComponent.Mixin.updateComponent.call(this, transaction, prevProps);
       var currentComponent = this._renderedComponent;
       var nextComponent = this._renderValidatedComponent();
-      invariant(
-        typeof currentComponent !== 'undefined',
-        'updateComponent(...): You are attempting to update an unrendered ' +
-        'component.'
-      );
       if (currentComponent.constructor === nextComponent.constructor) {
         currentComponent.receiveProps(nextComponent.props, transaction);
       } else {

src/core/__tests__/ReactComponentLifeCycle-test.js

@@ -408,6 +408,26 @@ describe('ReactComponentLifeCycle', function() {
       .toThrow();
   });
 
+  it('should throw when calling setProps() on an unmounted component', function() {
+    var PropsToUpdate = React.createClass({
+      render: function() {
+        return (
+          <input
+            value={this.props.value}
+            ref="theSimpleComponent">
+          </input>
+        );
+      }
+    });
+    var instance =
+      <PropsToUpdate
+        value="hello"
+      />;
+    expect(function() {
+      instance.setProps({value: "goodbye"});
+    }).toThrow();
+  });
+
   it('should allow state updates in componentDidMount', function() {
     /**
      * calls setState in an componentDidMount.