[v9.0.0-rc.1] "The `@nextcloud/vue` library was used without setting / replacing the `appName`"

Since 9.0.0-alpha.8 (and still with v9.0.0-rc.1) my app shows an error in the browser console:

chunk-MD7AZ4D5.js?v=b43cf7f5:91 [ERROR] @nextcloud/vue: The `@nextcloud/vue` library was used without setting / replacing the `appName`. {uid: 'johndoe', app: '@nextcloud/vue', level: 0}
log @ chunk-MD7AZ4D5.js?v=b43cf7f5:91
error @ chunk-MD7AZ4D5.js?v=b43cf7f5:109
(anonymous) @ appName.ts:15

I traced the cause down to src/utils/appName.ts:

try {
	// @ts-expect-error This is a  name replaces by the compiler
	realAppName = appName
} catch {
	logger.error('The `@nextcloud/vue` library was used without setting / replacing the `appName`.')
}

I don't understand what causes the exception. appName is defined and set to my application's name (tested within the entry script).

Possibly relevant because a "compiler" is involved: My app is built with vite and @nextcloud/vite-config.

Start with src/utils/appName.ts and reproduce the browser-console error in an app built with Vite and @nextcloud/vite-config. Trace why reading the compiler-replaced appName throws despite the entry script setting it. Done means identifying the cause and defining a verified fix or configuration change that prevents the error while preserving the application name.