Handle Malformed URIs Bug

You can slice an empty sequence:
```bash
renelvon @ merchant ~ % python2
Python 2.7.6 (default, Mar 22 2014, 22:59:56) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> ''[:120]
''
>>> 
```
so this is simpler as
```python
nickname = msg.get('senderNick', '')[:120]
```