ISSUE#31 Fixed panic on nil ptr

sheriff.go

@@ -7,7 +7,7 @@ import (
 	"reflect"
 	"strings"
 
-	version "github.com/hashicorp/go-version"
+	"github.com/hashicorp/go-version"
 )
 
 // Options determine which struct fields are being added to the output map.
@@ -217,6 +217,13 @@ func marshalValue(options *Options, v reflect.Value) (interface{}, error) {
 	}
 	k := v.Kind()
 
+	switch k {
+	case reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
+		if v.IsNil() {
+			return val, nil
+		}
+	}
+
 	if k == reflect.Ptr {
 		v = v.Elem()
 		val = v.Interface()

sheriff_test.go

@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"
 
-	version "github.com/hashicorp/go-version"
+	"github.com/hashicorp/go-version"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -713,3 +713,23 @@ func TestMarshal_EmptyInterface(t *testing.T) {
 	_, err := Marshal(o, v)
 	assert.NoError(t, err)
 }
+
+func TestMarshal_BooleanPtrMap(t *testing.T) {
+	tru := true
+
+	toMarshal := map[string]*bool{
+		"example": &tru,
+		"another": nil,
+	}
+
+	marshalMap, err := Marshal(&Options{}, toMarshal)
+	assert.NoError(t, err)
+
+	marshal, err := json.Marshal(marshalMap)
+	assert.NoError(t, err)
+
+	expect, err := json.Marshal(toMarshal)
+	assert.NoError(t, err)
+
+	assert.Equal(t, string(marshal), string(expect))
+}