test(chapter): PKG-CHAPTER-02 cover behavior and optional factory types

test/types/chapter-options.ts

@@ -0,0 +1,16 @@
+import type Artplayer from 'artplayer'
+import chapter from 'artplayer-plugin-chapter'
+
+declare const art: Artplayer
+chapter()
+chapter(undefined)
+chapter({})
+chapter({ chapters: [] })(art).update({})
+const name: 'artplayerPluginChapter' = chapter()(art).name
+void name
+// @ts-expect-error The update object remains required.
+chapter()(art).update()
+// @ts-expect-error A chapter title remains a string.
+chapter({ chapters: [{ start: 0, end: 1, title: 12 }] })
+// @ts-expect-error null is not an options object.
+chapter(null)