• 当前 Bug 的表现（可附上截图）

appservice?t=1546570096850:1862

Uncaught TypeError: Cannot read property ‘navigator’ of undefined

    at Object.202 (appservice?t=1546570096850:1862)

    at t (appservice?t=1546570096850:1862)

    at e.20 (appservice?t=1546570096850:1862)

    at appservice?t=1546570096850:1862

202 @ appservice?t=1546570096850:1862

t @ appservice?t=1546570096850:1862

e.20 @ appservice?t=1546570096850:1862

(anonymous) @ appservice?t=1546570096850:1862

• 预期表现

• 复现路径

• 提供一个最简复现 Demo