Unfinished long string literals generates valid ast

[ghost]

Test:

luaparse.parse('a = [====[]')

It generates valid ast, but should have thrown something like unfinished long string.

The long string literal value is also incorrect

console.log(
    luaparse.parse('a = [====[]').body[0].init[0].value // nothing.
  , luaparse.parse('a = [====[]]').body[0].init[0].value // ]
);

[fstirlitz]

Fixed in 07fbd6b.