NG05104: Root element was not found during bootstrap.

[niravupxselling]

I have a main project made in Angular 9,
and Web component applications made in angular 16.

adding angular 16 to angular 9 application.

facing an error in the console for bootstrapping.
It doesn't stop any functionality but shows an error.
element-chatbot.js is my one build file which is added in the angular 9 projects.

element-chatbot.js:2 ERROR Error: NG05104
at Ud.selectRootElement (element-chatbot.js:2:139887)
at w0 (element-chatbot.js:2:65882)
at ci.create (element-chatbot.js:2:65982)
at e.bootstrap (element-chatbot.js:2:107603)
at element-chatbot.js:2:105997
at Array.forEach ()
at e._moduleDoBootstrap (element-chatbot.js:2:105997)
at element-chatbot.js:2:105724
at push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (zone.js:386:1)
at Object.onInvoke (element-chatbot.js:2:98292)