Falling back to the lane-wide rows when a scoped fetch failed could still
blank the tables, since that window may hold none of the selected type,
and the failure went unreported. A lane-wide or scheduler-state failure
also threw before the scoped rows that did arrive were stored.
Each request now keeps its previous value on failure: the scoped rows
only while the tab is unchanged, otherwise the lane-wide rows. Whatever
arrived is stored and rendered, then the first failure is rethrown so the
caller reports it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
