Pbcopy crashes on use

### Checklist

- [x] Using latest version on the [App Store](http://itunes.apple.com/app/id1156707581)
- [x] Read the [docs](http://blink.sh/docs/)
- [x] Searched for [existing GitHub issues](https://github.com/blinksh/blink/issues)

### Configuration

### Describe the bug

Repro:

```bash
pbcopy [arguments]
```

Expected:
Copies, operation completes.

Actual:
Hangs on operation. Canceling operation with ctrl+C crashes the app.

Start by reproducing `pbcopy [arguments]` on the latest App Store version and trace the pbcopy command's handling of the copy operation and Ctrl+C cancellation. Done means the command copies successfully, completes without hanging, and canceling it does not crash the app.

Written by the indexing model from the issue text.