xpack-aria-describes="undefined" error in console while creating a threshold watch

[bhavyarm]

Kibana version: 7.x snapshot

Elasticsearch version: 7.x snapshot

Browser version: chrome latest

Original install method (e.g. download page, yum, from source, etc.): from snapshots

Describe the bug: If you click on threshold alert creation and start filling the form - You can see xpack-aria-describes="undefined" error in console.

console:

vendors.bundle.dll.js:499 Error: An element with xpack-aria-describes="undefined" does not have an id attribute defined
    at Object.link (kibana.bundle.js:3)
    at vendors.bundle.dll.js:499
    at invokeLinkFn (vendors.bundle.dll.js:499)
    at nodeLinkFn (vendors.bundle.dll.js:499)
    at compositeLinkFn (vendors.bundle.dll.js:499)
    at publicLinkFn (vendors.bundle.dll.js:499)
    at lazyCompilation (vendors.bundle.dll.js:499)
    at boundTranscludeFn (vendors.bundle.dll.js:499)
    at controllersBoundTransclude (vendors.bundle.dll.js:499)
    at ngIfWatchAction (vendors.bundle.dll.js:499) "<div id="{{watchEditTitlePanel.makeId(['indexSelectSearchBox', 'invalid'])}}" xpack-aria-describes="{{watchEditTitlePanel.makeId('indexSelectSearchBox')}}" class="kuiInputNote kuiInputNote--danger" ng-if="watchEditTitlePanel.showInvalidIndexValidationMessage()" i18n-id="xpack.watcher.sections.watchEdit.titlePanel.queryDoesNotMatchAnyValidIndicesValidationMessage" i18n-default-message="Your index query does not match any valid indices">"
(anonymous) @ vendors.bundle.dll.js:499
(anonymous) @ vendors.bundle.dll.js:499
invokeLinkFn @ vendors.bundle.dll.js:499
nodeLinkFn @ vendors.bundle.dll.js:499
compositeLinkFn @ vendors.bundle.dll.js:499
publicLinkFn @ vendors.bundle.dll.js:499
lazyCompilation @ vendors.bundle.dll.js:499
boundTranscludeFn @ vendors.bundle.dll.js:499
controllersBoundTransclude @ vendors.bundle.dll.js:499
ngIfWatchAction @ vendors.bundle.dll.js:499
$digest @ vendors.bundle.dll.js:499
$apply @ vendors.bundle.dll.js:499
done @ vendors.bundle.dll.js:499
completeRequest @ vendors.bundle.dll.js:499
requestLoaded @ vendors.bundle.dll.js:499
load (async)
(anonymous) @ vendors.bundle.dll.js:499
sendReq @ vendors.bundle.dll.js:499
serverRequest @ vendors.bundle.dll.js:499
processQueue @ vendors.bundle.dll.js:499
(anonymous) @ vendors.bundle.dll.js:499
$digest @ vendors.bundle.dll.js:499
$apply @ vendors.bundle.dll.js:499
(anonymous) @ vendors.bundle.dll.js:499
completeOutstandingRequest @ vendors.bundle.dll.js:499
(anonymous) @ vendors.bundle.dll.js:499
setTimeout (async)
Browser.self.defer @ vendors.bundle.dll.js:499
timeout @ vendors.bundle.dll.js:499
(anonymous) @ vendors.bundle.dll.js:556
$broadcast @ vendors.bundle.dll.js:499
ctrl.select @ vendors.bundle.dll.js:556
fn @ VM2683:4
callback @ vendors.bundle.dll.js:499
$eval @ vendors.bundle.dll.js:499
$apply @ vendors.bundle.dll.js:499
(anonymous) @ vendors.bundle.dll.js:499
dispatch @ vendors.bundle.dll.js:493
elemData.handle @ vendors.bundle.dll.js:493

[elasticmachine]

Pinging @elastic/es-ui