fix linting

pkg/river/encoding/array_test.go

@@ -8,9 +8,6 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-const number = "number"
-const age = "age"
-
 func TestSimpleArray(t *testing.T) {
 	intArr := make([]int, 10)
 	for i := 0; i < 10; i++ {

pkg/river/encoding/encoding.go

@@ -123,11 +123,6 @@ func isMapOrStruct(val value.Value) bool {
 	return val.Type() == value.TypeObject
 }
 
-func isStruct(val value.Value) bool {
-	// By checking the val.Type we can try to avoice the more expensive reflect.
-	return val.Type() == value.TypeObject && val.Reflect().Kind() == reflect.Struct
-}
-
 func convertRiverValue(val value.Value) (vf *ValueField, af *ArrayField, mf *MapField, err error) {
 	if isFieldValue(val) {
 		vf, err = convertValue(val)