fix linter errors

entry.go

@@ -123,11 +123,9 @@ func (entry *Entry) WithFields(fields Fields) *Entry {
 	for k, v := range fields {
 		isErrField := false
 		if t := reflect.TypeOf(v); t != nil {
-			switch t.Kind() {
-			case reflect.Func:
+			switch {
+			case t.Kind() == reflect.Func, t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Func:
 				isErrField = true
-			case reflect.Ptr:
-				isErrField = t.Elem().Kind() == reflect.Func
 			}
 		}
 		if isErrField {