fix missing chainID

Author: Tangui-Bitfly

backend/pkg/executionlayer/indexer.go

@@ -33,7 +33,9 @@ func (indexer *Indexer) IndexBlocks(chainID string, blocks []*types.Eth1Block) e
 }
 
 func (indexer *Indexer) IndexBlock(chainID string, block *types.Eth1Block) error {
-	var res IndexedBlock
+	res := IndexedBlock{
+		ChainID: chainID,
+	}
 	for _, transform := range indexer.transformers {
 		err := transform(chainID, block, &res)
 		if err != nil {