add: batch rpc calls

pkg/rpc/client.go

@@ -19,12 +19,24 @@ func NewRpcClient(endpoint string) RpcClient {
 func (r *RpcClient) EthRpcCall(method string) (*jsonrpc.RPCResponse, error) {
 	response, err := r.ethClient.Call(method)
 	if err != nil {
-		return response, err
+		return nil, err
 	}
 
 	if response.Error != nil {
-		return response, fmt.Errorf("rpc client error: (code %d) %s", response.Error.Code, response.Error.Message)
+		return nil, fmt.Errorf("rpc client error: (code %d) %s", response.Error.Code, response.Error.Message)
 	}
 
 	return response, nil
 }
+
+func (r *RpcClient) EthBatchRpcCall(batchedMethods jsonrpc.RPCRequests) (map[int]*jsonrpc.RPCResponse, error) {
+	response, _ := r.ethClient.CallBatch(batchedMethods)
+
+	if response.HasError() {
+		return nil, fmt.Errorf("batch rpc request failed")
+	}
+
+	results := response.AsMap()
+
+	return results, nil
+}