Javascript 处理嵌套承诺引发的异常

我不明白为什么我的应用程序会抛出一个未经处理的异常，或者我如何才能避免这个问题。异常在

拒绝（新错误（“…”）

行中抛出

引发异常的函数：

function parseSourceStrings(fileInformation, callback) {
    var filePath = fileInformation.path
    var fileExtension = path.extname(filePath)
    switch(fileExtension) {
        case '.pot':
        case '.po':
            return new Promise(function(resolve, reject) {
                poProcessor.processFile(filePath).then(function(result) {
                    result = addMetaData(fileInformation, result)
                    resolve(result)
                }).catch(function(err) {
                    reject(err)
                })
            })
        default:
            return new Promise(function(resolve, reject) {
                reject(new Error('Unknwown file format'))
            })
    }
}

mv(filePath, targetFilePath, {mkdirp: true}).then(function() {
    return uploadHandler.parseSourceStrings(fileInformation)
}).then(function(parsedSourceStrings) {
    console.log(parsedSourceStrings)
}).catch(function(err) {
    logger.error(err)
    next(err)
})

2:50:19 AM - error: Error: Unknwown file format
    at result.meta_information (c:\Users\h9pe\Documents\tms-reworked\app\projects\process-uploads\upload-handler.js:34:12)
    at Object.parseSourceStrings (c:\Users\h9pe\Documents\tms-reworked\app\projects\process-uploads\upload-handler.js:33:11)
    at c:\Users\h9pe\Documents\tms-reworked\app\projects\router.js:117:26
    at tryCatcher (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\util.js:16:23)
    at Promise.module.exports.Promise._settlePromiseFromHandler (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:512:31)
    at Promise.module.exports.Promise._settlePromise (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:569:18)
    at Promise.module.exports.Promise._settlePromise0 (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:614:10)
    at Promise.module.exports.Promise._settlePromises (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:693:18)
    at Promise.module.exports.Promise._fulfill (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:638:18)
    at module.exports (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\nodeback.js:42:21)
    at c:\Users\h9pe\Documents\tms-reworked\node_modules\mv\index.js:34:26
    at FSReqWrap.oncomplete (fs.js:123:15) '/projects/13/update/sourcestrings'

我就是这样调用函数的：

function parseSourceStrings(fileInformation, callback) {
    var filePath = fileInformation.path
    var fileExtension = path.extname(filePath)
    switch(fileExtension) {
        case '.pot':
        case '.po':
            return new Promise(function(resolve, reject) {
                poProcessor.processFile(filePath).then(function(result) {
                    result = addMetaData(fileInformation, result)
                    resolve(result)
                }).catch(function(err) {
                    reject(err)
                })
            })
        default:
            return new Promise(function(resolve, reject) {
                reject(new Error('Unknwown file format'))
            })
    }
}

mv(filePath, targetFilePath, {mkdirp: true}).then(function() {
    return uploadHandler.parseSourceStrings(fileInformation)
}).then(function(parsedSourceStrings) {
    console.log(parsedSourceStrings)
}).catch(function(err) {
    logger.error(err)
    next(err)
})

2:50:19 AM - error: Error: Unknwown file format
    at result.meta_information (c:\Users\h9pe\Documents\tms-reworked\app\projects\process-uploads\upload-handler.js:34:12)
    at Object.parseSourceStrings (c:\Users\h9pe\Documents\tms-reworked\app\projects\process-uploads\upload-handler.js:33:11)
    at c:\Users\h9pe\Documents\tms-reworked\app\projects\router.js:117:26
    at tryCatcher (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\util.js:16:23)
    at Promise.module.exports.Promise._settlePromiseFromHandler (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:512:31)
    at Promise.module.exports.Promise._settlePromise (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:569:18)
    at Promise.module.exports.Promise._settlePromise0 (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:614:10)
    at Promise.module.exports.Promise._settlePromises (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:693:18)
    at Promise.module.exports.Promise._fulfill (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:638:18)
    at module.exports (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\nodeback.js:42:21)
    at c:\Users\h9pe\Documents\tms-reworked\node_modules\mv\index.js:34:26
    at FSReqWrap.oncomplete (fs.js:123:15) '/projects/13/update/sourcestrings'

引发的异常：

function parseSourceStrings(fileInformation, callback) {
    var filePath = fileInformation.path
    var fileExtension = path.extname(filePath)
    switch(fileExtension) {
        case '.pot':
        case '.po':
            return new Promise(function(resolve, reject) {
                poProcessor.processFile(filePath).then(function(result) {
                    result = addMetaData(fileInformation, result)
                    resolve(result)
                }).catch(function(err) {
                    reject(err)
                })
            })
        default:
            return new Promise(function(resolve, reject) {
                reject(new Error('Unknwown file format'))
            })
    }
}

mv(filePath, targetFilePath, {mkdirp: true}).then(function() {
    return uploadHandler.parseSourceStrings(fileInformation)
}).then(function(parsedSourceStrings) {
    console.log(parsedSourceStrings)
}).catch(function(err) {
    logger.error(err)
    next(err)
})

2:50:19 AM - error: Error: Unknwown file format
    at result.meta_information (c:\Users\h9pe\Documents\tms-reworked\app\projects\process-uploads\upload-handler.js:34:12)
    at Object.parseSourceStrings (c:\Users\h9pe\Documents\tms-reworked\app\projects\process-uploads\upload-handler.js:33:11)
    at c:\Users\h9pe\Documents\tms-reworked\app\projects\router.js:117:26
    at tryCatcher (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\util.js:16:23)
    at Promise.module.exports.Promise._settlePromiseFromHandler (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:512:31)
    at Promise.module.exports.Promise._settlePromise (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:569:18)
    at Promise.module.exports.Promise._settlePromise0 (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:614:10)
    at Promise.module.exports.Promise._settlePromises (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:693:18)
    at Promise.module.exports.Promise._fulfill (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\promise.js:638:18)
    at module.exports (c:\Users\h9pe\Documents\tms-reworked\node_modules\bluebird\js\release\nodeback.js:42:21)
    at c:\Users\h9pe\Documents\tms-reworked\node_modules\mv\index.js:34:26
    at FSReqWrap.oncomplete (fs.js:123:15) '/projects/13/update/sourcestrings'

---

显然，这只是一个未处理的异常，但是捕获应该捕获抛出的异常没有？如何正确捕获异常？

FYI，您可以将第二行

reject（）

替换为

return Promise.reject（新错误（…）要短得多，切中要害。不确定原始行上出现错误的原因。是否确定这是一个未处理的错误，而不仅仅是
记录器的输出。错误（err）
您的异常是因为您的
parseSourceString（）
函数正在命中switch语句中的默认行，因此返回拒绝承诺。您对
uploadHandler.parseSourceStrings（fileInformation）
的调用随后被拒绝，这会导致您点击
.catch（）
，您会看到记录的错误。这看起来像是编码的，尽管可能您的代码得到了意外的文件扩展名。仅供参考-避免promise构造函数反模式-由于JSFIDLE，您的函数可以简化为@JaromandaX，因此蓝鸟默认拒绝捕获的异常，因为您已经使用了它？仅供参考，您可以替换第二个
拒绝（）
line with
return Promise.reject（新错误（…）；
要短得多，切中要害。不知道为什么在原始行上出现错误。你确定这是一个未处理的错误，而不仅仅是
logger的输出。错误（err）
你的异常是因为你的
parseSourceStrings（）
函数正在命中switch语句中的默认行，因此返回拒绝承诺。您对
uploadHandler.parseSourceStrings（fileInformation）
的调用将被拒绝，这将导致您命中
.catch（）
您会看到记录的错误。这似乎是按编码方式工作的，尽管您的代码可能会获得意外的文件扩展名。仅供参考-避免promise构造函数反模式-由于JSFIDLE，您的函数可以简化为@JaromandaX X，所以蓝鸟默认拒绝捕获的异常，因为您已经使用了它？