Bug: get_docx_document() returns truthy blank Document on missing template, silently writing empty output file #2490

Describe the bug

In scripts/convert.py, the get_docx_document() function is supposed to open and return a .docx template file. When the file does not exist, it logs an error but returns a blank docx.Document() instead of None. Since a blank docx.Document() is always truthy in Python, the caller's if doc: check always passes — causing the script to silently replace text in and save an empty document to the output path, producing a corrupted zero-content output file with no further error.

Affected file

scripts/convert.py — get_docx_document() and its call site in create_edition_from_template()

Code snippet

def get_docx_document(docx_file: str) -> Any:
    import docx
    if os.path.isfile(docx_file):
        return docx.Document(docx_file)
    else:
        logging.error("Could not find file at: %s", str(docx_file))
        return docx.Document()  # <-- blank Document, always truthy!

# Call site:
doc = get_docx_document(template_doc)
if doc:  # always True — even for a blank Document returned on error
    doc = replace_docx_inline_text(doc, language_dict)
    doc.save(output_file)  # saves an empty file with no content

Expected behavior

When the template file does not exist:

• get_docx_document() should return None
• The caller should detect None and skip the output file creation, or raise a clear error

Proposed fix

def get_docx_document(docx_file: str) -> Any:
    import docx
    if os.path.isfile(docx_file):
        return docx.Document(docx_file)
    else:
        logging.error("Could not find file at: %s", str(docx_file))
        return None  # caller already checks `if doc:`

Steps to reproduce

1. Specify a non-existent or missing template .docx file path
2. Run python scripts/convert.py -lt cards -l en -v 2.2
3. No error is raised; an empty .docx file is written to the output folder

Additional context

The docstring does not indicate that a blank fallback document will be returned on failure, making this behavior surprising and hard to diagnose. Returning None is cleaner, consistent with the existing if doc: guard in the caller, and avoids silently writing corrupt output files.