core/types: make "miner" optional in Header JSON (#24666)

"miner" is not set for pending block responses in some cases.

Fixes #24632

core/types/block.go

@@ -70,7 +70,7 @@ func (n *BlockNonce) UnmarshalText(input []byte) error {
 type Header struct {
 	ParentHash  common.Hash    `json:"parentHash"       gencodec:"required"`
 	UncleHash   common.Hash    `json:"sha3Uncles"       gencodec:"required"`
-	Coinbase    common.Address `json:"miner"            gencodec:"required"`
+	Coinbase    common.Address `json:"miner"`
 	Root        common.Hash    `json:"stateRoot"        gencodec:"required"`
 	TxHash      common.Hash    `json:"transactionsRoot" gencodec:"required"`
 	ReceiptHash common.Hash    `json:"receiptsRoot"     gencodec:"required"`

core/types/gen_header_json.go

@@ -18,7 +18,7 @@ func (h Header) MarshalJSON() ([]byte, error) {
 	type Header struct {
 		ParentHash  common.Hash    `json:"parentHash"       gencodec:"required"`
 		UncleHash   common.Hash    `json:"sha3Uncles"       gencodec:"required"`
-		Coinbase    common.Address `json:"miner"            gencodec:"required"`
+		Coinbase    common.Address `json:"miner"`
 		Root        common.Hash    `json:"stateRoot"        gencodec:"required"`
 		TxHash      common.Hash    `json:"transactionsRoot" gencodec:"required"`
 		ReceiptHash common.Hash    `json:"receiptsRoot"     gencodec:"required"`
@@ -60,7 +60,7 @@ func (h *Header) UnmarshalJSON(input []byte) error {
 	type Header struct {
 		ParentHash  *common.Hash    `json:"parentHash"       gencodec:"required"`
 		UncleHash   *common.Hash    `json:"sha3Uncles"       gencodec:"required"`
-		Coinbase    *common.Address `json:"miner"            gencodec:"required"`
+		Coinbase    *common.Address `json:"miner"`
 		Root        *common.Hash    `json:"stateRoot"        gencodec:"required"`
 		TxHash      *common.Hash    `json:"transactionsRoot" gencodec:"required"`
 		ReceiptHash *common.Hash    `json:"receiptsRoot"     gencodec:"required"`
@@ -87,10 +87,9 @@ func (h *Header) UnmarshalJSON(input []byte) error {
 		return errors.New("missing required field 'sha3Uncles' for Header")
 	}
 	h.UncleHash = *dec.UncleHash
-	if dec.Coinbase == nil {
-		return errors.New("missing required field 'miner' for Header")
+	if dec.Coinbase != nil {
+		h.Coinbase = *dec.Coinbase
 	}
-	h.Coinbase = *dec.Coinbase
 	if dec.Root == nil {
 		return errors.New("missing required field 'stateRoot' for Header")
 	}