workers: fix panics with schedQueue

storage/sealmgr/advmgr/manager.go

@@ -59,7 +59,7 @@ type Manager struct {
 	workerFree chan workerID
 	closing    chan struct{}
 
-	schedQueue list.List // List[*workerRequest]
+	schedQueue *list.List // List[*workerRequest]
 }
 
 func New(ls stores.LocalStorage, si stores.SectorIndex, cfg *sectorbuilder.Config, urls URLs, ca api.Common) (*Manager, error) {
@@ -97,6 +97,8 @@ func New(ls stores.LocalStorage, si stores.SectorIndex, cfg *sectorbuilder.Confi
 		workerFree: make(chan workerID),
 		closing:    make(chan struct{}),
 
+		schedQueue: list.New(),
+
 		Prover: prover,
 	}
 

storage/sealmgr/advmgr/sched.go

@@ -99,6 +99,9 @@ func (m *Manager) onWorkerFreed(wid workerID) {
 			if pe == nil {
 				pe = m.schedQueue.Front()
 			}
+			if pe == nil {
+				break
+			}
 			e = pe
 			continue
 		}