Handle failure for readFileSync

In node I can wrap a call to readFileSync in a synchronous try/catch:

```
var fs = require('fs');

try {
fs.readFileSync('./does/not/exist');
} catch (e) {
console.log('caught!');
}
```

and running it will write `caught!` but running through `browserify -t brfs` gives

```
events.js:72
throw er; // Unhandled 'error' event
^
Error: ENOENT, open './does/not/exist'
```

Is there a way that the same thing with brfs? I know that brfs processes the source statically, but I'm doing things like running the source through `envify` first and the fs call could fail and stop the build. Probably does so for the best, but I was wondering if there is a way to inline an empty string, undefined, etc.

Thanks substack!