Add test case for Alba's meta nil value

spec/__snapshots__/AlbaMetaNil.ts.snap

@@ -0,0 +1,9 @@
+// Typelizer digest 22be4653e9abf0c8b5e2963602fbf179
+//
+// DO NOT MODIFY: This file was automatically generated by Typelizer.
+
+type AlbaMetaNil = {
+  id: number;
+}
+
+export default AlbaMetaNil;

spec/__snapshots__/index.ts.snap

@@ -1,6 +1,7 @@
-// Typelizer digest cc9502b1f9ad666caf72dabb190670a0
+// Typelizer digest 3c3bed842a60e703fd96dab39cdc1cb5
 //
 // DO NOT MODIFY: This file was automatically generated by Typelizer.
+export type { default as AlbaMetaNil } from './AlbaMetaNil'
 export type { default as AlbaMeta } from './AlbaMeta'
 export type { default as AlbaPost } from './AlbaPost'
 export type { default as AlbaUserAuthor } from './AlbaUserAuthor'

spec/app/app/serializers/alba/meta_nil_serializer.rb

@@ -0,0 +1,8 @@
+module Alba
+  class MetaNilSerializer < BaseSerializer
+    typelize_from ::User
+    attributes :id
+
+    meta nil
+  end
+end