• 当前 Bug 的表现（可附上截图）

• 预期表现

• 复现路径

• 提供一个最简复现 Demo

不总出现，四五次出现一次，怎么解决求助

TypeError: Cannot read property ‘beforeAll’ of undefined

    at WAService.js:12

    at n (WAService.js:6)

    at e (appservice?t=1556594641410:1680)

    at r.registerCallback.t (appservice?t=1556594641410:1680)

    at u.forEach.t (appservice?t=1556594641410:1680)

    at Array.forEach (<anonymous>)

    at appservice?t=1556594641410:1680

    at WebSocket.a.onmessage (appservice?t=1556594641410:1680)