feat: add cast_utils.dart (castAsOrNull, castAsNullable)

lib/src/cast_utils.dart

@@ -1,6 +1,6 @@
 /// Future compat to always return nullable.
-T? castAsNullable<T extends Object>(T? value) => value;
+T? castAsNullable<T extends Object?>(T? value) => value;
 
 /// Safe cast
-T? castAsOrNull<T extends Object>(Object? object) =>
+T? castAsOrNull<T extends Object?>(Object? object) =>
     object is T ? object : null;

pubspec.yaml

@@ -1,5 +1,5 @@
 name: tekartik_common_utils
-version: 0.15.2
+version: 0.15.2+1
 description: Common pure dart utilities (not io or browser dependant)
 homepage: https://github.com/tekartik/common_utils.dart
 publish_to: none

test/cast_utils_test.dart

@@ -7,6 +7,10 @@ void main() {
 
   group('cast_utils', () {
     test('castAsNullable', () {
+      expect(castAsNullable<int>(null), isNull);
+      expect(castAsNullable<int>(1), 1);
+      expect(castAsNullable<int?>(null), isNull);
+
       void nullableFunction(int? value) {}
       void nonNullFunction(int value) {}
       nonNullableInt = 1;
@@ -23,6 +27,7 @@ void main() {
       expect(castAsOrNull<int>(1), 1);
       expect(castAsOrNull<int>('1'), isNull);
       expect(castAsOrNull<int>(null), isNull);
+      expect(castAsOrNull<int?>(null), isNull);
     });
   });
 }