TypeError: Cannot set property '_isHover' of null

報過好多次這種錯誤

[Vue warn]: Error in callback for watcher "data": "TypeError: Cannot set property '_isHover' of null"

found in

---> <Table>

TypeError: Cannot set property '_isHover' of null
    at VueComponent.eval (iview.js?f489:22929)
    at Array.forEach (<anonymous>)
    at VueComponent.makeObjData (iview.js?f489:22925)
    at VueComponent.handler (iview.js?f489:23076)
    at Watcher.run (vue.runtime.esm.js?3a00:3345)
    at flushSchedulerQueue (vue.runtime.esm.js?3a00:3087)
    at Array.eval (vue.runtime.esm.js?3a00:1916)
    at flushCallbacks (vue.runtime.esm.js?3a00:1835)

從幾次調數據的情況看，是賦值了一個undefined