String as a second argument won't appear in logs

# Bug Description

# How to reproduce

```
const logger = new Logger();
const err = new Error('This is second argument');

logger.log('This is message.', err.message);  // show `This is message.` only.
```

# Expected behavior
Shows both, like
```
logger.log('This is message.', err.message);  // show `This is message. This is second argument`.
```