Reverts f73d8e6d49. While there are other ways to achieve some of the same end results, this code existed in the code base for 8 months without issues and is included in the official docs. This means that there could be devs that are depending on this behavior. Additionally, while this may make the internal logic to the BackendController class more complex, it simplifies the developer experience by bringing the Backend\Classes\Controller base class more in line with the standard Laravel controller class.
For some reason it was decided to allow October controllers to support Laravel middleware, this has been reverted because it is a convoluted solution that doesn't respect the original architecture. There are other ways to handle middleware requirements
The original use case appeared to be to simply allow backend controllers to inject headers. This is something easily solvable whilst keeping the simple and original workflow
An exception was thrown when loading middleware if a requested controller is from a disabled plugin, as the `getRequestedController` method returns a Response object in this scenario.
Hat tip to @w20k.
This is for flat-file sites that don't use a database. If debug mode is on, it will show an error page with advice to set up the database. If debug mode is off, it will simply show a 404 page. Previously it was a nasty exception/plain error page.