message: Fix stacktrace test for node v10
  Node.js v10 is returning the function name as `'Object.beforeEach'`
  rather than `'Object.<anonymous>'`. By moving the code that throws the
  error out of an anonymous function and into a named function, we can
  avoid this ambiguity.
diff: @@ -5,12 +5,16 @@ describe('stacktracejs processor', () => {
  let error;
  describe('Error', () => {
  - beforeEach(() => {
  + function throwTestError() {
  try {
  throw new Error('BOOM');
  } catch (err) {
  error = espProcessor(err);
  }
  + }
  +
  + beforeEach(() => {
  + throwTestError();
  });
  it('provides type and message', () => {
  @@ -24,7 +28,7 @@ describe('stacktracejs processor', () => {
  let frame = backtrace[0];
  expect(frame.file).toContain('tests/processor/stacktracejs.test');
  - expect(frame.function).toBe('Object.<anonymous>');
  + expect(frame.function).toBe('throwTestError');
  expect(frame.line).toEqual(expect.any(Number));
  expect(frame.column).toEqual(expect.any(Number));
  });
  