kvserver: add two r.mu.Unlock before Fatal

Just for hygiene.

Author: tbg

pkg/kv/kvserver/replica_raftstorage.go

@@ -642,8 +642,10 @@ func (r *Replica) applySnapshot(
 	if isInitialSnap {
 		// NB: this will also call setDescLockedRaftMuLocked.
 		if err := r.initFromSnapshotLockedRaftMuLocked(ctx, desc); err != nil {
+			r.mu.Unlock()
 			log.Fatalf(ctx, "unable to initialize replica while applying snapshot: %+v", err)
 		} else if err := r.store.markReplicaInitializedLockedReplLocked(ctx, r); err != nil {
+			r.mu.Unlock()
 			log.Fatalf(ctx, "unable to mark replica initialized while applying snapshot: %+v", err)
 		}
 	} else {