what do you think of this:

```javascript
var args = ...,
    stack = new Error().stack;

if (stack) {
  ...
}

var messages = args;
if (type === 'trace') {
  messages = stack;
  type = 'log';
}
...
```

And then you can remove the 'trace' handler in runner-stream-proxy.js.

What do you think?