mono-error v1.0.0

mono-error

Provide a way to add context to Errors by including metadata and wrapping errors. When throwing an Error, the function usually doesn't have very much context about state in the caller. Having parent functions catch errors and re-throw them with additional messages or metadata can give very helpful state to have when debugging.

Error handling with asyncronous code (callbacks, promises, async-await) typically have bad stacktraces that are incomplete or unreadable without sourcemaps. Wrapping errors and extending the message with 'caused by' is a simple way to add readable information about the chain of execution in asyncronous situations.

DetailedError

DetailedError is an Error that includes a details object, which defaults to having the stack as a property.

function updateLocation(x: int, y: int) {
    throw new DetailedError('failed to do stuff', { x, y });
}

WrappedError

WrappedError can be used to wrap any error with additional metadata to be re-thrown. It extends DetailedError. These errors preserve the original stack, and adds a 'caused by' message to the error, similar to chaining Exceptions in Java.

function doStuff(id: int) {
    try {
        `...`
    } catch (err) {
        throw new WrappedError(err, 'failed to do stuff', { id });
    }
}

Error Details

The details on the error is a simple object that is easy to log via analytics or a logger like winston. The 'stack' property on details should get picked up by winston transports for rollbar or stackdriver

try {
    `...`
} catch (err) {
    if (err instanceof DetailedError) {
        winston.error(err.msg, err.details)
    }
}