How to execute the if statement correctly so that an error does not appear

I use Laravel and I have the following problem – when I execute the function, the following error “Call to a member function prepare() on null” appears, but I want this error not to appear, but to execute the function in the if statement. Here is part of the code

 public function saveWizard(Request $request, Redirector $redirect)
{

    $rules = config('installer.environment.form.rules');
    $messages = [
        'environment_custom.required_if' => trans('installer_messages.environment.wizard.form.name_required'),
    ];

    $validator = Validator::make($request->all(), $rules, $messages);

    if ($validator->fails()) {
        return $redirect->route('LaravelInstaller::environmentWizard')->withInput()->withErrors($validator->errors());
    }

    $check = $this->checkDatabaseConnection($request);

    if (!$check) {
        return $redirect->route('LaravelInstaller::environmentWizard')->withInput()->withErrors([
            'database_connection' => trans('installer_messages.environment.wizard.form.db_connection_failed'),
        ]);
    }

    $results = $this->EnvironmentManager->saveFileWizard($request);

    event(new EnvironmentSaved($request));

    return $redirect->route('LaravelInstaller::database')
                    ->with(['results' => $results]);
}

and checkDatabaseConnection function

private function checkDatabaseConnection(Request $request)
{
    $connection = $request->input('database_connection');

    $settings = config("database.connections.$connection");

    config([
        'database' => [
            'default' => $connection,
            'connections' => [
                $connection => array_merge($settings, [
                    'driver' => $connection,
                    'host' => $request->input('database_hostname'),
                    'port' => $request->input('database_port'),
                    'database' => $request->input('database_name'),
                    'username' => $request->input('database_username'),
                    'password' => $request->input('database_password'),
                ]),
            ],
        ],
    ]);

    DB::purge();

    try {
        DB::connection()->getPdo();

        return true;
    } catch (Exception $e) {
        return false;
    }
}