src/error-proto.js
function ErrorFunction(message: string) {
  const Err = /*::Object.assign({}, callAssign, */Error/*::)*/
  Err.call(this, message)
  if (noFallback) {
    Error.captureStackTrace(this, ErrorFunction)
  } else {
    this.stack = (new Error()).stack
  }
  this.name = this.constructor.name
  this.message = message
}
function ErrorFunction(message: string) {
  const Err = /*::Object.assign({}, callAssign, */Error/*::)*/
  Err.call(this, message)
  if (noFallback) {
    Error.captureStackTrace(this, ErrorFunction)
  } else {
    this.stack = (new Error()).stack
  }
  this.name = this.constructor.name
  this.message = message
}
/*::
const callAssign = {
call(thisFn: any, arg: string){

}
}

class ExtendableErrorClass extends Error {}