Created attachment 326656 [details]
Example error log

Occasionally, search highlights missing from a search result, and "Error highlighting search results: ... - database disk image is malformed" is reported in the debug log.

Seems the issue might be the use of 'offsets()' in the Geary.ImapDB.Account::do_get_search_matches query occasionally flaking out:

> sqlite> SELECT docid, offsets(MessageSearchTable) FROM MessageSearchTable WHERE docid IN (757) AND MessageSearchTable MATCH 'fr*';
> Error: database disk image is malformed
> sqlite> SELECT docid FROM MessageSearchTable WHERE docid IN (757) AND MessageSearchTable MATCH 'fr*';
> 757

Here, docid 757 contains several strings that match "fr*", and also has some empty columns (attachment, cc, bcc), which looks like a SQLIte issue in earlier versions, i.e.: <http://sqlite.1065341.n5.nabble.com/regression-in-FTS3-offsets-function-in-3-6-23-td15216.html> and <http://www.sqlite.org/src/info/9861b74ab9>.

Since I am using SQLite 3.11.0 this may be a regression, although I can't reproduce the issue in the same way as in the nabble post above with this version, even when using unicodesn as the tokeniser.