Sequencers and Text Extractors should only log a warning if an exception occurs after the repository has been shut down

Currently sequencing and text extracting is done off separate worker threads (and in some cases in different modules) than the main application thread.
In the cases when exceptions occur during this work, they are normally logged as errors with a full stack trace of the original exception.
However, in certain cases these exceptions can occur after a repository has been shut down or is in the shutting down process, making the output of the full exception stack trace much less useful.

We need to make the appropriate changes to make sure that:

• exceptions raised by sequencers and text extractors bubble up to the owning "worker" thread
• in turn, the "worker" thread either logs the exception as an ERROR with the full stack trace and all other meaningful information (like the property paths in the case of sequencers) or logs a generic (simple) WARNING if a repository has been shut down.