Only register an option once in strict mode (#3692)

I'm not 100% sure this is the right fix but it _does_ fix keyboard
navigation in listbox and menu when using strict mode.

Basically the same items/options are being registered more than once and
that causes the arrow up/down logic to only advance on every other
keypress.

Author: thecrypticace

packages/@headlessui-react/src/components/listbox/listbox-machine.ts

@@ -426,10 +426,17 @@ export class ListboxMachine<T> extends Machine<State<T>, Actions<T>> {
     },
     registerOption: batch(() => {
       let options: { id: string; dataRef: ListboxOptionDataRef<T> }[] = []
+      let seen = new Set<ListboxOptionDataRef<T>>()
+
       return [
-        (id: string, dataRef: ListboxOptionDataRef<T>) => options.push({ id, dataRef }),
+        (id: string, dataRef: ListboxOptionDataRef<T>) => {
+          if (seen.has(dataRef)) return
+          seen.add(dataRef)
+          options.push({ id, dataRef })
+        },
         () => {
-          this.send({ type: ActionTypes.RegisterOptions, options: options.splice(0) })
+          seen.clear()
+          return this.send({ type: ActionTypes.RegisterOptions, options: options.splice(0) })
         },
       ]
     }),

packages/@headlessui-react/src/components/menu/menu-machine.ts

@@ -366,10 +366,18 @@ export class MenuMachine extends Machine<State, Actions> {
     // Batched version to register multiple items at the same time
     registerItem: batch(() => {
       let items: { id: string; dataRef: MenuItemDataRef }[] = []
+      let seen = new Set<MenuItemDataRef>()
 
       return [
-        (id: string, dataRef: MenuItemDataRef) => items.push({ id, dataRef }),
-        () => this.send({ type: ActionTypes.RegisterItems, items: items.splice(0) }),
+        (id: string, dataRef: MenuItemDataRef) => {
+          if (seen.has(dataRef)) return
+          seen.add(dataRef)
+          items.push({ id, dataRef })
+        },
+        () => {
+          seen.clear()
+          return this.send({ type: ActionTypes.RegisterItems, items: items.splice(0) })
+        },
       ]
     }),
     unregisterItem: batch(() => {