Set "custom" withErrors without Request->validation in Laravel

I want to display an error in a form, but it cannot be checked via validation.

Blade

    <form action="/githubuser" methode="GET">
        <div class="error">{{ $errors->first('CustomeError') }}</div>
        <input type="text" name="userName" placeholder="GitHub Username ..." value="John12341234">
        @if($errors->has('userName'))
            <div class="error">{{ $errors->first('userName') }}</div>
        @endif            
        <input type="submit" value="SUBMIT">
    </form>

The Problem is that I start an api call after validation. and if I don’t get "GitHubUser" as a response, I want to print an error message in the blade. GitHub user not found.

Controller

    public function show(Request $request)
    {
        $rules = ['userName' => 'required'];
        $validator = \Validator::make($request->input(), $rules);
        
        if ($validator->fails()) {
            return redirect('/')
                    ->withErrors($validator)
                    ->withInput();
        }
        
        $data = $this->gitHubUserService->getUserData($request->input('userName'));
        /* User on Github not Found **/
        if (! $data) {
            // >>> THE LINE BELOW IS MY PROBLEM! <<<
            return view('form')->withErrors($validator);
        }

        // ....
     }

At the end of the day I want the line <div class="error">{{ $errors->first('CustomeError') }}</div> to be displayed in the blade.

Is this possible? Thanks in advance!

>Solution :

The original validator is not getting any error, because there are none. So, just add a new error to the errors inside of your if body before returning form view:

if(! $data){
    $validator->errors()->add('customError', 'Github User not found!');
    return view('form')->withErrors($validator);
}