What steps will reproduce the problem?
1. Be in party with other user having addon
2. Other party member complete series of quests.
3. Perhaps different zone though i believe error presents in same zone at times.
4. Does not happen for every quest and does not seem to present with any interface issues as of yet.

What is the expected output? What do you see instead?
user completed blah blah quest. following error to "non-questor" is given instead.

What version of the product are you using?
v2.

Do you have an error log of what happened?
1x BetterQuest-v2\modules\sink\sink.lua:107 attempt to concatenate local 'title' (a boolean value)
CallbackHandler-1.0-6:147: in function <...ist\libs\CallbackHandler-1.0\CallbackHandler-1.0.lua:147
<string>:"safecall Dispatcher[4]":4: in function <[string "safecall Dispatcher[4]"]:4>
<in C code>: ?
<string>:"safecall Dispatcher[4]":13: in function `?'
CallbackHandler-1.0-6:92: in function `Fire'
LibQuixote-2.0-90093:567: in function `?'
LibQuixote-2.0-90093:598: in function `?'
LibQuixote-2.0-90093:118: in function <...ns\BetterQuest\lib\LibQuixote-2.0\LibQuixote-2.0.lua:117

Please provide any additional information below.
This seems to pop up often just wanted to post it for your review.