WowAce

What steps will reproduce the problem?
I'm not sure, but it's like:
1. Start a cast and enter some zone that enforces cast cancell
2.When a cast is cancelled, the following error is displayed

What is the expected output? What do you see instead?
IDK what should be displayed; An error is shown.

What version of the product are you using?
3.2.3

Do you have an error log of what happened?
Message: Interface\AddOns\Quartz\modules\Interrupt-Прерв..lua:58: <unnamed>:SetFormattedText(): Font not set
Time: 12/06/14 22:45:07
Count: 1
Stack: Interface\AddOns\Quartz\modules\Interrupt.lua:58: in function `?'
...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0.lua:147: in function <...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0.lua:147>
[string "safecall Dispatcher[18]"]:4: in function <[string "safecall Dispatcher[18]"]:4>
[C]: ?
[string "safecall Dispatcher[18]"]:13: in function `?'
...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0.lua:92: in function `Fire'
Interface\AddOns\Ace3\AceEvent-3.0\AceEvent-3.0.lua:120: in function <Interface\AddOns\Ace3\AceEvent-3.0\AceEvent-3.0.lua:119>

Locals: <none

This bug is triggered when Interrupt module is enabled, but player cast bar is disabled, because the interrupt module is trying to set the text of a disabled bar. Maybe the addon must disable the interrupt module if the player castbar is disabled.