TYPO3 Core

If you install TYPO3 via composer you have the possibility to use a nested directory as "web-dir". During the installation an exception is thrown because the DefaultFactory of ext:install does not take this nested path apart and makes only one DirectoryNode out of it.
Such a structure is suitable for e.g. headless applications with separate front end.

Example part for custom web-dir configuration:

"extra": {
    "typo3/cms": {
      "web-dir": "public/api" 
    }
  }