❔ The helper method 'Problem()' isn't in my controller scope. Pls help!

The helper method 'Problem()' isn't in my scope despite inheriting ControllerBase. When I scan the GitHub repo the method is part of the ControllerBase class. https://github.com/dotnet/aspnetcore/blob/06f1d1de4ff60e88ee0134fc827a7703ba739325/src/Mvc/Mvc.Core/src/ControllerBase.cs#L1857

GitHub

aspnetcore/ControllerBase.cs at 06f1d1de4ff60e88ee0134fc827a7703ba7...

ASP.NET Core is a cross-platform .NET framework for building modern cloud-based web applications on Windows, Mac, or Linux. - aspnetcore/ControllerBase.cs at 06f1d1de4ff60e88ee0134fc827a7703ba73932...