Different route behavior when using different backends

Example
```
(ql:quickload '(:weblocks :weblocks-ui :weblocks-navigation-widget))

(defpackage todo
(:use #:cl
#:weblocks-ui/form
#:weblocks/html)
(:import-from #:weblocks/widget
#:render
#:update
#:defwidget)
(:import-from #:weblocks/actions
#:make-js-action)
(:import-from #:weblocks/app
#:defapp)
(:import-from #:weblocks-navigation-widget
#:defroutes))

(in-package todo)

(defapp tasks
:prefix "/")

(defwidget task ()
())

(defmethod render ((task task))
(with-html (:h1 "Test")))

(defroutes test
("/" (make-instance 'task)))

(defmethod weblocks/session:init ((app tasks))
(declare (ignorable app))
(make-test))

```

when using :`(weblocks/server:start :port 40000 :server-type :hunchentoot :interface "127.0.0.1")`, you should get "Test" from 127.0.0.1:4000
But both
`(weblocks/server:start :port 40000 :server-type :wookie :interface "127.0.0.1")` and
`(weblocks/server:start :port 40000 :server-type :woo :interface "127.0.0.1")` give error like this:
```
;;woo, from repl
Callback Error: the message-complete callback failed
The value of WEBLOCKS/ROUTES::PATH is NIL, which is not of type STRING.
```
```
;;wookie, from 127.0.0.1:4000
There was an error processing your request: The value
NIL
is not of type
SIMPLE-STRING
when binding STRING
```
Where am I wrong?