IndexException
Base class for every failure the indexing layer raises on its own account.
Deliberately not a subclass of StoreException, and for the same reason CatalogException is not: that type is sealed and should stay sealed, because a caller catching it is asking about the storage engine. An index sidecar that will not decode has not cost anybody a document — every failure here is repaired by rebuilding the sidecar from the segment it describes, which is the whole point of keeping indexes outside the data.
Ordinary IO failures are not wrapped, matching the core and the catalog: a full disk is an java.io.IOException and the operating system's own diagnosis is the useful part of it.