[6.x] Link fieldtype throws Javascript error

[martyf]

Bug description

With Statamic Alpha 19, and the Link fieldtype, selecting "Entry" from the list throws a JS error in the console.

Uncaught TypeError: can't access property "$el", this.$refs.input.$refs.existing is undefined
    linkExistingItem http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:313
    option http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:311
    setTimeout handler*option http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:311
    callWithErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    callWithAsyncErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    call http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    Nt http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    callWithErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    flushJobs$1 http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    promise callback*queueFlush$1 http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    queueJob$1 http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    scheduler http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    trigger http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    endBatch http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    notify http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    trigger http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    set value http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    pn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:157
    onSelect http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:157
    callWithErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    callWithAsyncErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    emit http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    0 http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:131
    callWithErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    callWithAsyncErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    emit http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    Xe http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:131
    handleAndDispatchCustomEvent http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:131
    Qe http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:131
    callWithErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    callWithAsyncErrorHandling http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:17
    U http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:26
    addEventListener http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:26
    patchEvent http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:26
    patchProp http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:26
    Lt http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    It http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    xt http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    qn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    run http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    rn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    sn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    tn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    xt http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    qn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    run http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    rn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    sn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    tn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    xt http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    qn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    run http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    rn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    sn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    tn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    xt http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    qn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    run http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:10
    rn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    sn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    tn http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
    xt http://s6-plain.test/vendor/statamic/cp/build/assets/index-B6t0AjCd.js:18
index-B6t0AjCd.js:313:10316

After this happens, the CP behaves erratically (i.e. Cmd+S no longer works) and if you manually click save, changes sometimes get lost.

How to reproduce

1. Clean Statamic 6 Alpha 19 install
2. Edit the "Page" Blueprint to add a Link field
3. Edit the Home page
4. Change "Link Field" to "Entry"
5. Error appears in console

Logs

Environment

Environment
Application Name: Statamic
Laravel Version: 12.43.1
PHP Version: 8.4.15
Composer Version: 2.9.2
Environment: local
Debug Mode: ENABLED
URL: s6-plain.test
Maintenance Mode: OFF
Timezone: UTC
Locale: en

Cache
Config: NOT CACHED
Events: NOT CACHED
Routes: NOT CACHED
Views: CACHED

Drivers
Broadcasting: log
Cache: file
Database: sqlite
Logs: stack / single
Mail: log
Queue: sync
Session: file

Storage
public/storage: NOT LINKED

Statamic
Addons: 0
Sites: 1
Stache Watcher: Enabled (auto)
Static Caching: Disabled
Version: 6.0.0-alpha.19 PRO

Installation

Fresh statamic/statamic site via CLI

Additional details

No response