[]TypeError: Cannot read property '_byteLength' of null

(LayaAirIDE1.7.11版本)TypeError: Cannot read property '_byteLength' of null
at WebGLContext2D.__proto.flush (file:///F:/client_svn/h5/bin/libs/laya.webgl.js:4963:32)
at SubmitCanvas.__proto.renderSubmit (file:///F:/client_svn/h5/bin/libs/laya.webgl.js:6294:18)
at WebGLContext2D.__proto.submitElement (file:///F:/client_svn/h5/bin/libs/laya.webgl.js:4954:30)
at WebGLContext2D.__proto.flush (file:///F:/client_svn/h5/bin/libs/laya.webgl.js:4976:9)
at RenderContext.__proto.flush (file:///F:/client_svn/h5/bin/libs/laya.core.js:5569:31)
at Stage.__proto.render (file:///F:/client_svn/h5/bin/libs/laya.core.js:17348:14)
at Stage.__proto._loop (file:///F:/client_svn/h5/bin/libs/laya.core.js:17274:9)
at loop (file:///F:/client_svn/h5/bin/libs/laya.core.js:5061:16)