go/worker/storage/committee: Fix prune handler

In case of empty state DB, last synced round is set to max uint64
value, thus the worker prunes light history even if it should not do it.

Author: martintomazic

.changelog/6445.bugfix.md

@@ -0,0 +1,4 @@
+go/worker/storage/committee: Fix prune handler
+
+Prune handler had an edge case when State DB was empty,
+which could cause runtime light history to be pruned prematurely.

go/worker/storage/committee/prune.go

@@ -20,6 +20,9 @@ type pruneHandler struct {
 // Implements runtime.history.PruneHandler.
 func (p *pruneHandler) CanPruneRuntime(rounds []uint64) error {
 	lastSycnedRound, _, _ := p.worker.GetLastSynced()
+	if lastSycnedRound == defaultUndefinedRound {
+		return fmt.Errorf("worker/storage: tried to prune past last synced round (empty state db)")
+	}
 
 	for _, round := range rounds {
 		if round >= lastSycnedRound {