generateView at 'onRequest' extension point #1137

I'm trying to use request.generateView to generate a custom error page in an 'onRequest' extension function, like so:

server.ext('onRequest', function (request, next) {
  if (errorCondition)
    next(request.generateView('error', {message: 'Foo'}))
  else
    next()
})

request.generateView fails in request.js:716 with

Debug: hapi, uncaught, onRequest, error TypeError: Cannot read property 'env' of null
    at internals.Request.generateView (.../node_modules/hapi/lib/request.js:716:35)

Changing request.js:716 to

    var viewsManager = (this._route && this._route.env.views) || this.server._views;

in order to guard against missing this._route seems to fix it, but I don't know if that's the correct fix. I'm not sure if calling request.generateView at that point is supposed to be supported at all.