Does not work correctly when there is no leading whitespace on line

[kachkaev]

Steps to reproduce:

1. Open test/index.ts

2. Replace

  const ast = jsonAST(`
  obj:
    arr:
    - nums:
      - 1
      - 2
      - 3
      strs1:
      - '1'
      - '2'
      - '3'
    str: '1'
    num: 1
  `);

with

  const ast = jsonAST(`
obj:
  arr:
  - nums:
    - 1
    - 2
    - 3
    strs1:
    - '1'
    - '2'
    - '3'
  str: '1'
  num: 1
  `);

3. Run yarn test and see them failing

Thanks for this useful package guys! I'll see if I can help!