Parsing error

OS: Windows 10 21H2
Python: Python 3.10.4

Steps:

• pip install pyquotes

example.py

'''
Example File
'''

A = "This is a test string."
B = 'This is a test string.'
C = "This isn't a test string, or is it?"
D = f"{A}{B}{C}"
E = f'{A}{B}{C}'

• pyquotes example.py
• pyquotes --check example.py
• pyquotes -D example.py
• pyquotes -D --check example.py

All fail with the error

  File "C:\Python310\lib\site-packages\parso\python\tree.py", line 86, in get_doc_node
    c = simple_stmt.parent.children
AttributeError: 'NoneType' object has no attribute 'children'

If a print('Hello, World!') is added to the file, it behaves as expected.

Thank you for your time, this library has saved my many hours.

[ThiefMaster]

Works fine for me... (tested on Python 3.9 though)

Narrowed it down further, although I realize this is a PEP8 violation, it occurs if there is no new line and the last character is a closing quote. (Checked on Python 3.9 to match you)

[ThiefMaster]

OK, I'm inclined to say "garbage in, garbage out" (text/code files should ALWAYS contain a trailing linebreak), but if it's not a bug in parso but pyquotes and can be easily fixed I'll accept a PR for it.

Traceback (most recent call last):
  File "C:\Python39\lib\runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Python39\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Python39\Scripts\pyquotes.exe\__main__.py", line 7, in <module>
  File "C:\Python39\lib\site-packages\click\core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
  File "C:\Python39\lib\site-packages\click\core.py", line 1055, in main
    rv = self.invoke(ctx)
  File "C:\Python39\lib\site-packages\click\core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "C:\Python39\lib\site-packages\click\core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "C:\Python39\lib\site-packages\pyquotes\cli.py", line 89, in main
    changed = _process_file(file, config=config)
  File "C:\Python39\lib\site-packages\pyquotes\cli.py", line 114, in _process_file
    new_code = transform_source(old_code, double_quotes=config.double_quotes)
  File "C:\Python39\lib\site-packages\pyquotes\transform.py", line 49, in transform_source
    for is_doc, leaf in _iter_strings(tree):
  File "C:\Python39\lib\site-packages\pyquotes\transform.py", line 42, in scan
    yield from scan(node)
  File "C:\Python39\lib\site-packages\pyquotes\transform.py", line 29, in scan
    doc_node = parent.get_doc_node()
  File "C:\Python39\lib\site-packages\parso\python\tree.py", line 86, in get_doc_node
    c = simple_stmt.parent.children
AttributeError: 'NoneType' object has no attribute 'children'

This is the full stack trace, and confirmed it doesn't happen for example if the contents is print("Test") without a newline.