laravel-boilerplate Undefined index: /css/frontend.css issue 500 Internal Server Error - development

laravel-boilerplate Undefined index: /css/frontend.css issue 500 Internal Server Error

I’m getting error in laravel boilerplate after changed
in to

Undefined index: /css/frontend.css (View: /var/www/html/intranetapp-middleware/resources/views/frontend/layouts/app.blade.php) (View: /var/www/html/laravel-boilerplate/resources/views/frontend/layouts/app.blade.php)

but i removed my changes as per original ,still error comming….

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