fixed crash when there is a renderable w/o a mesh
fixed crash when there is a renderable w/o a mesh

JakubLukas/LumixEngine,JakubLukas/LumixEngine,zhouxh1023/LumixEngine,dreamsxin/LuxEngine,JakubLukas/LumixEngine,zhouxh1023/LumixEngine,galek/LumixEngine,gamedevforks/LumixEngine,gamedevforks/LumixEngine,galek/LumixEngine,dreamsxin/LuxEngine