Json error handler
    Returns a json message for th excepion with appripriate response code and
    application/json content type.
    :param exception:
    :return:

def json_error_handler(exception):
    """
    Json error handler
    Returns a json message for th excepion with appripriate response code and
    application/json content type.
    :param exception:
    :return:
    """
    http_exception = isinstance(exception, exceptions.HTTPException)
    code = exception.code if http_exception else 500

    # log exceptions only (app debug should be off)
    if code == 500:
        current_app.logger.error(exception)

    response = jsonify(dict(message=str(exception)))
    response.status_code = code
    return response