eth/catalyst: return 0x0 on Invalid block on top of pow block (ethereum#25006)

Author: MariusVanDerWijden

eth/catalyst/api.go

@@ -361,7 +361,12 @@ func computePayloadId(headBlockHash common.Hash, params *beacon.PayloadAttribute
 func (api *ConsensusAPI) invalid(err error, latestValid *types.Block) beacon.PayloadStatusV1 {
 	currentHash := api.eth.BlockChain().CurrentBlock().Hash()
 	if latestValid != nil {
-		currentHash = latestValid.Hash()
+		// Set latest valid hash to 0x0 if parent is PoW block
+		currentHash = common.Hash{}
+		if latestValid.Difficulty().BitLen() == 0 {
+			// Otherwise set latest valid hash to parent hash
+			currentHash = latestValid.Hash()
+		}
 	}
 	errorMsg := err.Error()
 	return beacon.PayloadStatusV1{Status: beacon.INVALID, LatestValidHash: &currentHash, ValidationError: &errorMsg}

eth/catalyst/api_test.go

@@ -648,7 +648,8 @@ func TestEmptyBlocks(t *testing.T) {
 	if status.Status != beacon.INVALID {
 		t.Errorf("invalid status: expected INVALID got: %v", status.Status)
 	}
-	expected := commonAncestor.Hash()
+	// Expect 0x0 on INVALID block on top of PoW block
+	expected := common.Hash{}
 	if !bytes.Equal(status.LatestValidHash[:], expected[:]) {
 		t.Fatalf("invalid LVH: got %v want %v", status.LatestValidHash, expected)
 	}