Potential null reference leads to NullPointerException

Original reporter: posttk421

Steps to reproduce:

1. Login as an Administrator
2. Install the AutoCompletion Application
3. Create a page and edit it in wiki mode
4. Insert this content: 

   {{box cssClass="floatinginfobox"}} {{velocity}}

1. Activate the autocomplete using this shortcut: CTRL+SPACE

Expected result:

Nothing happens as there is no autocomplete needed.

Actual result:

An error is shown.saying "Failed to get autocompletion: Server error"