Merge pull request #2419 from filecoin-project/schomatis/fix/newtipset/mismatch-lengths

fix: NewTipSet: check mismatch in number of parents

chain/types/tipset.go

@@ -112,6 +112,10 @@ func NewTipSet(blks []*BlockHeader) (*TipSet, error) {
 			return nil, fmt.Errorf("cannot create tipset with mismatching heights")
 		}
 
+		if len(blks[0].Parents) != len(b.Parents) {
+			return nil, fmt.Errorf("cannot create tipset with mismatching number of parents")
+		}
+
 		for i, cid := range b.Parents {
 			if cid != blks[0].Parents[i] {
 				return nil, fmt.Errorf("cannot create tipset with mismatching parents")