- 当前 Bug 的表现（可附上截图）

退出小程序，进入后，报这个错误，反复进入，反复出现。

        thirdScriptError
        Cannot read property 'emit' of undefined;at api connectSocket fail callback function
        TypeError: Cannot read property 'emit' of undefined
            at fail (weapp:///sdk/lib/weapp.socket.io.js:1026:16)
            at Function.function.e.(anonymous function) ([publib]:1:682757)
            at Function.<anonymous> ([publib]:1:101865)
            at Object.fail ([publib]:1:101865)
            at Ve ([publib]:1:276294)
            at Object.<anonymous> ([publib]:1:277380)
            at v ([publib]:1:990)
            at [publib]:1:1129
            at Object._ [as invoke] ([publib]:1:1287)
            at Object.invoke ([publib]:1:117397)

- 预期表现

socket正常连接

- 复现路径

- 提供一个最简复现 Demo