internal/ethapi: eth_call block parameter is optional (ethereum#28165)

So apparently in the spec the base block parameter of eth_call is optional.
I agree that "latest" is a sane default for this that most people would use.

internal/ethapi/api.go

@@ -1087,8 +1087,12 @@ func (e *revertError) ErrorData() interface{} {
 //
 // Note, this function doesn't make and changes in the state/blockchain and is
 // useful to execute and retrieve values.
-func (s *PublicBlockChainAPI) Call(ctx context.Context, args TransactionArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides *StateOverride) (hexutil.Bytes, error) {
-	result, err := DoCall(ctx, s.b, args, blockNrOrHash, overrides, s.b.RPCEVMTimeout(), s.b.RPCGasCap())
+func (s *PublicBlockChainAPI) Call(ctx context.Context, args TransactionArgs, blockNrOrHash *rpc.BlockNumberOrHash, overrides *StateOverride) (hexutil.Bytes, error) {
+	if blockNrOrHash == nil {
+		latest := rpc.BlockNumberOrHashWithNumber(rpc.LatestBlockNumber)
+		blockNrOrHash = &latest
+	}
+	result, err := DoCall(ctx, s.b, args, *blockNrOrHash, overrides, s.b.RPCEVMTimeout(), s.b.RPCGasCap())
 	if err != nil {
 		return nil, err
 	}