defaultGetStackString = error => {
  if (!('stack' in error)) {
    return '';
  }
  const stackString = `${error.stack}`;
  const pos = stringIndexOf(stackString, '\n');
  if (stringStartsWith(stackString, ' ') || pos === -1) {
    return stackString;
  }
  return stringSlice(stackString, pos + 1); // exclude the initial newline
}
The unprivileged form that just uses the de facto `error.stack` property.
The start compartment normally has a privileged `globalThis.getStackString`
which should be preferred if present.

@param {Error} error
@returns {string}