TypeError: Cannot read property 'clear' of null

Cocos Creator
#1 
TypeError: Cannot read property 'clear' of null
1498
    at Object.genRenderDatas (C:\CocosCreator\resources\engine\bin\.cache\dev\extensions\spine\spine-assembler.js:114:29)
    at Object.updateRenderData (C:\CocosCreator\resources\engine\bin\.cache\dev\extensions\spine\spine-assembler.js:221:26)
    at RenderFlow._proto._updateRenderData (C:\CocosCreator\resources\engine\bin\.cache\dev\cocos2d\core\renderer\render-flow.js:89:29)
    at RenderFlow._proto._children (C:\CocosCreator\resources\engine\bin\.cache\dev\cocos2d\core\renderer\render-flow.js:117:38)
    at Function.render (C:\CocosCreator\resources\engine\bin\.cache\dev\cocos2d\core\renderer\render-flow.js:198:42)
    at RenderComponentWalker.visit (C:\CocosCreator\resources\engine\bin\.cache\dev\cocos2d\core\renderer\webgl\render-component-walker.js:146:28)
    at Object.render (C:\CocosCreator\resources\engine\bin\.cache\dev\cocos2d\core\renderer\index.js:125:34)
    at cc.Director.mainLoop.CC_EDITOR._purgeDirectorInNextLoop [as mainLoop] (C:\CocosCreator\resources\engine\bin\.cache\dev\cocos2d\core\CCDirector.js:441:26)
    at EditorEngine.tickInEditMode (C:\CocosCreator\resources\app.asar\editor\page\scene-utils\editor-engine\index.js:1:2597)
    at EditorEngine._tick (C:\CocosCreator\resources\app.asar\editor\page\scene-utils\editor-engine\index.js:1:5622)

This error is frequent. Please help in v2.0.9
@jare @slackmoehrle