fix: edge when can not get epoch response

Signed-off-by: Marko Kungla <marko.kungla@gmail.com>

address.go

@@ -215,7 +215,7 @@ func (c *Client) GetCredentialTxs(
 	return res, ReadAndUnmarshalResponse(rsp, &res.Response, &res.Data)
 }
 
-// String returns of address
+// String returns of address.
 func (a Address) String() string {
 	return string(a)
 }

address_test.go

@@ -141,7 +141,7 @@ func (s *addressTestSuite) TestGetCredentialTxsEndpoint() {
 	}
 }
 
-// Requires more tests with supported address formats
+// Requires more tests with supported address formats.
 func (s *addressTestSuite) TestInvalidAddress() {
 	var tests = []struct {
 		Addr koios.Address
@@ -175,5 +175,7 @@ func (s *addressTestSuite) TestBytes() {
 		0x6b, 0x34, 0x77, 0x36, 0x71, 0x72, 0x78, 0x33,
 		0x70, 0x39, 0x38, 0x7a, 0x61, 0x64, 0x33, 0x66,
 		0x71, 0x30, 0x37, 0x78, 0x65, 0x39, 0x67},
-		koios.Address("addr1qyp9kz50sh9c53hpmk3l4ewj9ur794t2hdqpngsjn3wkc5sztv9glpwt3frwrhdrltjaytc8ut2k4w6qrx3p98zad3fq07xe9g").Bytes())
+		koios.Address(
+			"addr1qyp9kz50sh9c53hpmk3l4ewj9ur794t2hdqpngsjn3wkc5sztv9glpwt3frwrhdrltjaytc8ut2k4w6qrx3p98zad3fq07xe9g",
+		).Bytes())
 }

epoch.go

@@ -18,6 +18,7 @@ package koios
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/shopspring/decimal"
 )
@@ -214,6 +215,11 @@ func (c *Client) GetEpochParams(
 	if err != nil {
 		return
 	}
+
 	err = ReadAndUnmarshalResponse(rsp, &res.Response, &res.Data)
+
+	if len(res.Data) == 0 {
+		return nil, fmt.Errorf("%w: could not get epoch params %s", ErrResponse, epoch)
+	}
 	return
 }