message: Fix error message test
diff: @@ -6,8 +6,7 @@ export function runErrorsTests() {
  test('InvalidDIDError', (t) => {
  t.plan(3)
  const error = new InvalidDIDError('the message')
  -
  - t.equal(error.message, 'the message')
  + t.equal(error.message.indexOf('the message'), 0)
  t.equal(error.parameter, null)
  t.equal((<any>error).param, undefined)
  })
  