Using Winston in typescript

I can't figure how to use the logging module Winston in typescript. I have an error when I try to set the logger level, and another one when I try to log an error:

import * as logger from "winston";

logger.level = 'debug';
// [ts] Cannot assign to 'level' because it is a constant or a read-only property.

logger.error(new Error('test'));
// [ts] Argument of type 'Error' is not assignable to parameter of type 'string'.

I have added both winston and @types/winston to my project.

Edit: to complete Joshua answer, it seem that by default winston logs to... nowhere. You have to add a transport to make it work:

import * as logger from "winston";

logger.configure({
    level: 'debug',
    transports: [
        new logger.transports.Console({
            colorize: true
        })
    ]
});