x/gov: fix rest single vote and inactive proposal votes list queries (#6388)

* Fix single vote and votes list issues

* Add unmarshal json test

x/gov/client/rest/query.go

@@ -313,7 +313,7 @@ func queryVoteHandlerFn(clientCtx client.Context) http.HandlerFunc {
 // todo: Split this functionality into helper functions to remove the above
 func queryVotesOnProposalHandlerFn(clientCtx client.Context) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		_, page, limit, err := rest.ParseHTTPArgsWithLimit(r, 0)
+		_, page, limit, err := rest.ParseHTTPArgs(r)
 		if rest.CheckBadRequestError(w, err) {
 			return
 		}

x/gov/types/vote.go

@@ -109,6 +109,11 @@ func (vo *VoteOption) UnmarshalJSON(data []byte) error {
 		return err
 	}
 
+	if s == "" {
+		*vo = OptionEmpty
+		return nil
+	}
+
 	bz2, err := VoteOptionFromString(s)
 	if err != nil {
 		return err

x/gov/types/vote_test.go

@@ -0,0 +1,36 @@
+package types
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestVoteUnMarshalJSON(t *testing.T) {
+	tests := []struct {
+		option  string
+		isError bool
+	}{
+		{"Yes", false},
+		{"No", false},
+		{"Abstain", false},
+		{"NoWithVeto", false},
+		{"", false},
+		{"misc", true},
+	}
+	for _, tt := range tests {
+		var vo VoteOption
+		data, err := json.Marshal(tt.option)
+		require.NoError(t, err)
+
+		err = vo.UnmarshalJSON(data)
+		if tt.isError {
+			require.Error(t, err)
+			require.EqualError(t, err, fmt.Sprintf("'%s' is not a valid vote option", tt.option))
+		} else {
+			require.NoError(t, err)
+		}
+	}
+}