Upload file with GraphQL +Ariadne + Flask: graphql.error.graphql_error.GraphQLError: Operation data should be a JSON object

@graphql_bp.route("/", methods=["POST"])
def graphql_server():
    if request.content_type.startswith("multipart/form-data"):
        data = combine_multipart_data(
            json.loads(request.form.get("operations")),
            json.loads(request.form.get("map")),
            dict(request.files)
        )
    else:
        data = request.get_json()
    success, result = graphql_sync(
        schema,
        data,
        context_value=request,
        debug=current_app.debug
    )
    status_code = 200 if success else 400
    return jsonify(result), status_code