fix: add check that $ref value is a string (asyncapi#92)

Co-authored-by: Maciej Urbańczyk <[email protected]>

tests/lib/index.spec.ts

@@ -44,6 +44,9 @@ describe('bundler should ', () => {
  test('should not throw if value of `$ref` is not a string', async () => {
  const files = ['./tests/wrong-ref-not-string.yaml'];
 
+ // If async function `bundle()` resolved Promise successfully, that means it
+ // did not throw exception during process of execution, which is the
+ // objective of testing.
  expect(
  await bundle(
  files.map(file =>
@@ -59,6 +62,9 @@ describe('bundler should ', () => {
  test('should not throw if value of `$ref` is absent', async () => {
  const files = ['./tests/wrong-ref-absent.yaml'];
 
+ // If async function `bundle()` resolved Promise successfully, that means it
+ // did not throw exception during process of execution, which is the
+ // objective of testing.
  expect(
  await bundle(
  files.map(file =>