fix: ensure JSON serialization compatibility

Because Tendermint encodes ints as strings, and expects strings while
decoding, Optimint has to encode int values as strings as well.

Resolves cosmos#463.

rpc/json/handler.go

@@ -10,6 +10,8 @@ import (
 	"reflect"
 	"strconv"
 
+	tmjson "github.com/tendermint/tendermint/libs/json"
+
 	"github.com/celestiaorg/optimint/log"
 	"github.com/gorilla/rpc/v2"
 	"github.com/gorilla/rpc/v2/json2"
@@ -176,7 +178,12 @@ func (h *handler) encodeAndWriteResponse(w http.ResponseWriter, result interface
 	if errResult != nil {
 		resp.Error = &json2.Error{Code: json2.ErrorCode(statusCode), Data: errResult.Error()}
 	} else {
-		resp.Result = result
+		bytes, err := tmjson.Marshal(result)
+		if err != nil {
+			resp.Error = &json2.Error{Code: json2.ErrorCode(json2.E_INTERNAL), Data: err.Error()}
+		} else {
+			resp.Result = bytes
+		}
 	}
 
 	encoder := json.NewEncoder(w)

rpc/json/service_test.go

@@ -68,13 +68,13 @@ func TestREST(t *testing.T) {
 
 		{"invalid/malformed request", "/block?so{}wrong!", http.StatusOK, int(json2.E_INVALID_REQ), ``},
 		{"invalid/missing param", "/block", http.StatusOK, int(json2.E_INVALID_REQ), `missing param 'height'`},
-		{"valid/no params", "/abci_info", http.StatusOK, -1, `"last_block_height":345`},
+		{"valid/no params", "/abci_info", http.StatusOK, -1, `"last_block_height":"345"`},
 		// to keep test simple, allow returning application error in following case
 		{"valid/int param", "/block?height=321", http.StatusOK, int(json2.E_INTERNAL), `"key not found"`},
 		{"invalid/int param", "/block?height=foo", http.StatusOK, int(json2.E_PARSE), "failed to parse param 'height'"},
 		{"valid/bool int string params",
 			"/tx_search?" + txSearchParams.Encode(),
-			http.StatusOK, -1, `"total_count":0`},
+			http.StatusOK, -1, `"total_count":"0"`},
 		{"invalid/bool int string params",
 			"/tx_search?" + strings.Replace(txSearchParams.Encode(), "true", "blue", 1),
 			http.StatusOK, int(json2.E_PARSE), "failed to parse param 'prove'"},

rpc/json/types.go

@@ -161,7 +161,7 @@ func unmarshalStrInt64(b []byte, s *StrInt64) error {
 
 type response struct {
 	Version string          `json:"jsonrpc"`
-	Result  interface{}     `json:"result,omitempty"`
+	Result  json.RawMessage `json:"result,omitempty"`
 	Error   *json2.Error    `json:"error,omitempty"`
 	Id      json.RawMessage `json:"id"`
 }