Child array recursion limited

During my internal testing, it seems to fail when `"html":"[]"` contains more than 2 elements... :thinking:

```bash
Received:
{"<>":"div","class":"${class}", "id":"${id}","html":[{"<>":"img", "src":"${src}","alt":"${alt}"},{"<>":"p","text":"Hi ${name}! Welcome to json2html!"},{"<>":"p","text":"Awesome it works!"}]}
Traceback (most recent call last):
File "json2html.test.py", line 347, in
main()
File "json2html.test.py", line 344, in main
json2html.transform(payload, data)
File "json2html.test.py", line 289, in transform
cls._merge(debug)
File "json2html.test.py", line 148, in _merge
if (cls.props[j]['iteration'] == cls.props[i]['iteration']):
IndexError: list index out of range
```