Redirecting item leads to error about missing data

[dpriskorn]

LeMyst/WikibaseIntegrator#917 (comment)
code is here

def create_redirect(from_id: str, to_id: str, login: _Login | None = None) -> dict[str, Any]:
    """
    Clear the item `from_id` and create a redirect to `to_id`.
    """
    log.info(f"Creating redirect from {from_id} → {to_id}")

    try:
        # Step 1: Clear the item
        clear_payload = {
            "action": "wbeditentity",
            "id": from_id,
            "clear": "true",
            "summary": f"Clearing {from_id} to prepare for redirect",
            "format": "json"
        }
        clear_response = mediawiki_api_call_helper(data=clear_payload, login=login, is_bot=True)
        if "error" in clear_response:
            log.error(f"Failed to clear {from_id}: {clear_response['error']}")
            return clear_response
        else:
            log.debug(f"Cleared successfully: {clear_response}")

        # Step 2: Create the redirect
        redirect_payload = {
            "action": "wbcreateredirect",
            "from": from_id,
            "to": to_id,
            "data": "{}",
            "format": "json"
        }
        redirect_response = mediawiki_api_call_helper(data=redirect_payload, login=login, is_bot=True)
        if "error" in redirect_response:
            log.error(f"Failed to create redirect {from_id} → {to_id}: {redirect_response['error']}")
        else:
            log.info(f"Redirect created successfully: {from_id} → {to_id}")

        return redirect_response

    except Exception as e:
        log.error(f"Exception when creating redirect {from_id} → {to_id}: {e}")
        return {"error": str(e)}

def merge_items_and_create_redirect(
    qids: List[str],
    login: _Login | None = None,
    ignore_conflicts: List[str] | None = None,
    is_bot: bool = False,
    tags: Union[str, List[str]] | None = None,
    **kwargs: Any
) -> str:
    """
    Merge multiple Wikibase items into the lowest QID.

    :param qids: List of item QIDs to merge. The lowest QID will be kept.
    :param login: A wbi_login.Login instance
    :param ignore_conflicts: List of elements to ignore conflicts for. Can contain "description", "sitelink", "statement"
    :param is_bot: Mark this edit as bot
    :param tags: Single tag string or list of tags to attach to the edit
    :param kwargs: Additional parameters to pass to mediawiki_api_call_helper
    """
    if not qids or len(qids) < 2:
        raise ValueError("You must provide at least two QIDs to merge")

    # Sort QIDs numerically to keep the lowest
    sorted_qids = sorted(qids, key=lambda x: int(x.lstrip('Q')))
    to_id = sorted_qids[0]          # keep the lowest QID
    from_ids = sorted_qids[1:]      # merge all other QIDs into to_id

    # Prepare tags string if provided
    tags_str = None
    if tags:
        if isinstance(tags, list):
            tags_str = '|'.join(tags)
        else:
            tags_str = str(tags)

    for from_id in from_ids:
        params = {
            'action': 'wbmergeitems',
            'fromid': from_id,
            'toid': to_id,
            'format': 'json'
        }

        if ignore_conflicts is not None:
            params['ignoreconflicts'] = '|'.join(ignore_conflicts)

        if is_bot:
            params['bot'] = ''

        if tags_str:
            params['tags'] = tags_str

        try:
            mediawiki_api_call_helper(data=params, login=login, is_bot=is_bot, **kwargs)
            print(f"Merged {from_id} into {to_id}")
            create_redirect(from_id=from_id, to_id=to_id, login=login)
            return to_id
        except Exception as e:
            print(f"Error merging {from_id} into {to_id}: {e}")