TypeError: "O is undefined" with url parameters

I'm using flask-apispec with flask-restful
Example of view

```
from flask_restful import Resource, Api
from apispec import APISpec
from apispec.ext.marshmallow import MarshmallowPlugin
from flask_apispec.extension import FlaskApiSpec

api = Api(app)

app.config.update({
'APISPEC_SPEC': APISpec(
authorizations=authorizations,
title='pets',
version='v1',
plugins=[MarshmallowPlugin()],
openapi_version="3.0.3",
),
'APISPEC_SWAGGER_URL': '/swagger/',
})

class ListView(MethodResource):
def get(self, type_id, list_id):
#some code

api.add_resource(ListView, '/api/types//lists//')
docs = FlaskApiSpec(app)
docs.register(ListView)

```

and when I open Swagger UI i get

Start with the Flask-RESTful example in the issue and reproduce the Swagger UI failure for the route containing type_id and list_id. Trace how flask-apispec registers ListView and generates the OpenAPI path parameters; done means the documented route loads in Swagger UI without the “O is undefined” error.

Written by the indexing model from the issue text.