title: react-native Unhandled JS Exception: null is not an object (evaluating 't.componentWillU
body: <p>I realize this the error log may not be that meaningful, but I am getting this error on both Android and iOS. I am not able to reproduce this, but some users are getting this, pretty randomly. I am using react-native-v0.25rc.</p>
  
  <p>How should I start debugging this kind of problem?</p>
  
  <p><code>
  Unhandled JS Exception: null is not an object (evaluating 't.componentWillU..., stack: unmountComponent@153:1757 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 unmountComponent@153:1823 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 unmountComponent@153:1823 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 unmountComponent@153:1823 unmountComponent@133:347 unmountComponent@153:1823 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 unmountComponent@153:1823 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 unmountComponent@153:1823 unmountComponent@133:347 unmountChildren@196:681 unmountChildren@195:2369 unmountComponent@194:397 unmountComponent@133:347 updateChildren@196:568 _reconcilerUpdateChildren@195:1026 _updateChildren@195:1922 updateChildren@195:1787 receiveComponent@194:1061 receiveComponent@133:505 updateChildren@196:420 _reconcilerUpdateChildren@195:1026 _updateChildren@195:1922 updateChildren@195:1787 receiveComponent@194:1061 receiveComponent@133:505 _updateRenderedComponent@153:4625 _performComponentUpdate@153:4394 updateComponent@153:3671 performUpdateIfNecessary@153:3192 performUpdateIfNecessary@133:667 r@131:571 perform@136:494 perform@136:494 perform@131:1539 P@131:1711 closeAll@136:1131 perform@136:581 batchedUpdates@130:456 s@131:761 a@150:69 enqueueSetState@150:917 setState@58:315 _cleanScenesPastIndex@232:15460 &lt;unknown&gt;@232:14104 _completeTransition@232:5658 onSpringAtRest@232:2811 notifyPositionUpdated@251:6971 advance@251:6732 advance@251:1772 loop@251:2223 i@251:8270 callTimer@31:707 callTimers@31:882 value@27:3098 &lt;unknown&gt;@27:1317 k@27:411 value@27:1289
  </code></p>