Koa框架I18n语言包报错问题

项目的运行日志中出现了如下报错：

TypeError: ctx.i18n[(SET_PREFIX + key)] is not a function
      at ctx.i18n.whitelist.some.key (/explorer/web-explore/node_modules/koa-i18n/index.js:107:59)
      at Array.some (<anonymous>)
      at i18nMiddleware (/explorer/web-explore/node_modules/koa-i18n/index.js:104:24)
      at dispatch (/explorer/web-explore/node_modules/koa-compose/index.js:42:32)
      at /explorer/web-explore/node_modules/koa-compose/index.js:34:12
      at Application.handleRequest (/explorer/web-explore/node_modules/koa/lib/application.js:151:12)
      at Server.handleRequest (/explorer/web-explore/node_modules/koa/lib/application.js:133:19)
      at Server.emit (events.js:198:13)
      at parserOnIncoming (_http_server.js:677:12)
      at HTTPParser.parserOnHeadersComplete (_http_common.js:109:17)

这就导致了站点在部分浏览器如Firefox上会出现internet server error的问题。 定位到node_modules/koa-i18n/index.js文件中的107行：

return function i18nMiddleware(ctx, next) {
    ctx.i18n.whitelist.some(key => {
      const customLocaleMethod = typeof key === 'function'
        && ctx.i18n.setLocale(key.apply(ctx))
      if (customLocaleMethod || ctx.i18n[SET_PREFIX + key]()) return true
    })
    return next()
  }

使用类型判断typeof ctx.i18n[SET_PREFIX + key]()这个方法发现很多都是undefined也不想找了，直接try catch掉，改为如下代码：

return function i18nMiddleware(ctx, next) {
    ctx.i18n.whitelist.some(key => {
      const customLocaleMethod = typeof key === 'function'
        && ctx.i18n.setLocale(key.apply(ctx))
        try{
            if (customLocaleMethod || ctx.i18n[SET_PREFIX + key]()) return true
        }catch(e){
        }
      //if (customLocaleMethod/* || ctx.i18n[SET_PREFIX + key]()*/) return true
    })
    return next()
  }