Log errors to stdout/err

When first starting the
```
Pyroscope.init({
serverAddress: 'https://pyroscope.cloud',
appName: 'nodejs-test',
})

Pyroscope.start()
```
And error was thrown:
```
throw 'Pyroscope is not configured. Please call init() first.';
```

But I was calling `init`, which is confusing.

By setting the `DEBUG` environment variable, the error message is shown:
```bash
DEBUG='pyroscope*' node main.js
pyroscope Pyroscope is running on a cloud server, but no authToken was provided. Pyroscope will not be able to ingest data. +1ms
```

Therefore we should just log that message to stdout/err instead of hiding behind an env var.