TwingLoaderFileSystem is not a constructor

I'm trying to use Twing but Hapi is not playing along.

I keep getting the same error even if I put the code in a empty space somewhere in a file.

err: {
      "type": "TypeError",
      "message": "TwingLoaderFilesystem is not a constructor",
      "stack":
          TypeError: TwingLoaderFilesystem is not a constructor
              at Object.compile (/Users/rickdgraaff/Projects/rickdegraaff.nl/config/server_settings.js:32:46)
              at Object.Manager.engine.compileFunc (/Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/vision/lib/manager.js:92:50)
              at /Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/vision/lib/manager.js:367:20
              at new Promise (<anonymous>)
              at Manager._compile (/Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/vision/lib/manager.js:365:16)
              at async Manager._prepareTemplates (/Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/vision/lib/manager.js:287:34)
              at async Object.internals.prepare (/Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/vision/lib/manager.js:571:32)
              at async exports.Manager.execute (/Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/hapi/lib/toolkit.js:105:28)
              at async Object.internals.handler (/Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/hapi/lib/handler.js:46:20)
              at async exports.execute (/Users/rickdgraaff/Projects/rickdegraaff.nl/node_modules/@hapi/hapi/lib/handler.js:31:20)