prevent nil pointer crash

consensus/quorum/one-node-staked-vote.go

@@ -173,11 +173,13 @@ func (v *stakedVoteWeight) computeTotalPowerByMask(mask *bls_cosi.Mask) *numeric
 
 	for key, i := range mask.PublicsIndex {
 		if enabled, err := mask.IndexEnabled(i); err == nil && enabled {
+			if voter, ok := v.roster.Voters[key]; ok {
 				currentTotal = currentTotal.Add(
-				v.roster.Voters[key].OverallPercent,
+					voter.OverallPercent,
 				)
 			}
 		}
+	}
 	return &currentTotal
 }