Incorrect LambdaHandler type

[AndKiel]

Exported LambdaHandler type allows only sync functions even though AWS also supports async lambdas:

rollbar.js/index.d.ts

Line 35 in bf9a2ef

export type LambdaHandler<E = object> = (event: E, context: object, callback: Callback) => void;

Rollbar's internal logic also seems to support both sync and async:

rollbar.js/src/server/rollbar.js

Line 284 in 63c2f64

Rollbar.prototype.lambdaHandler = function(handler, timeoutHandler) {

but due to the incorrect type declaration linting and/or building of a project can fail.

Possibly Rollbar could use https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/aws-lambda/handler.d.ts types for consistency with aws-lambda package.