I think this PR #366 while having positive impact can turn working code into broken one after wrapping dynamic strings into HEREDOC:

> code = "\"\\n\n \#{x}\""
> ast = Unparser.parse(code)
=> s(:dstr,
  s(:str, "\n\n"),
  s(:str, " "),
  s(:begin,
    s(:send, nil, :x)))
> processed_code = Unparser.unparse(ast)
=> "<<-HEREDOC\n\n\n \#{x}HEREDOC\n"
> Unparser.parse(processed_code)
=> Parser::SyntaxError: unterminated string meets end of file (Parser::SyntaxError)

Feels like we are missing a newline before the closing HEREDOC.

PS
There is an "easy" fix that would check the content of the heredoc and see whether there is a newline at the end, if not perform chomp. But that deviates from the original AST meaning the provided code is not semantically the same.

Haven't found a better solution though. At least it produces parseable code and evaluates to the same value.