We have had occasions where the indexing failed, sometimes involving a lingering Lucene lock file. That's a tricky part of the system, and it's possible to reindex when that happens. No big deal.

The problem is that users are not notified that something bad is happening. For example, we had Assignees pulling their reports of things to do, but the lists were incomplete due because of an indexing problem. However, since these failures directly affect the integrity of the information on the screen, some message should be shown to whatever user causes this IndexingException to occur so that they can notify our admins to fix something (specifically, by reindexing).

It has been suggested that we monitor our logs for things like "IndexException" (JSP-1454 on support.atlassian.com), which we will do. But I highly recommend immediate user notification when this kind of thing happens.