refactor: responses to PR review

Author: ARR4N

core/types/backwards_compat.libevm_test.go

@@ -31,7 +31,7 @@ import (
 )
 
 func newTx(nonce uint64) *Transaction    { return NewTx(&LegacyTx{Nonce: nonce}) }
-func newHdr(hashLow byte) *Header        { return &Header{ParentHash: common.Hash{hashLow}} }
+func newHdr(parentHashHigh byte) *Header { return &Header{ParentHash: common.Hash{parentHashHigh}} }
 func newWithdraw(idx uint64) *Withdrawal { return &Withdrawal{Index: idx} }
 
 func blockBodyRLPTestInputs() []*Body {

core/types/rlp_payload.libevm.go

@@ -206,7 +206,7 @@ func (ExtraPayloads[HPtr, BPtr, SA]) cloneStateAccount(s *StateAccountExtra) *St
 // blockOrBody is an interface for use as a method argument as they can't
 // introduce new generic type parameters.
 type blockOrBody interface {
-	isBlockOrBody() // noop purely for tagging
+	isBlockOrBody() // noop to restrict type as [Header.extraPayload] otherwise matches
 	extraPayload() *pseudo.Type
 }