Exception in rendering!

Message: Cannot read property 'document_key' of null

TypeError: Cannot read property 'document_key' of null
    at Header.render (<anonymous>:61701:59)
    at ReactCompositeComponentWrapper._renderValidatedComponentWithoutOwnerOrContext (<anonymous>:128343:30)
    at ReactCompositeComponentWrapper._renderValidatedComponent (<anonymous>:128366:32)
    at ReactCompositeComponentWrapper.performInitialMount (<anonymous>:127906:30)
    at ReactCompositeComponentWrapper.mountComponent (<anonymous>:127802:21)
    at Object.mountComponent (<anonymous>:11065:35)
    at ReactCompositeComponentWrapper.performInitialMount (<anonymous>:127915:34)
    at ReactCompositeComponentWrapper.mountComponent (<anonymous>:127802:21)
    at Object.mountComponent (<anonymous>:11065:35)
    at ReactDOMComponent.mountChildren (<anonymous>:131315:44)