Code review comment for lp:~vikoadi/slingshot/async_update_menu

That's cool :)

However, as we discussed a few minutes ago, there is 2 main issues:

* Please add some Mutex, this way it is not thread safe, in AppSystem *and* in SynapseSearch.
* In the async function, if the thread creation fails, the function never finish, not sure it is a good thing, the yield should probably be before the catch.

(also some code style issues written in the diff comments)