Description of the problem:
When entering the workflow definition page, the workflow viewer is not shown

How reproducible:
100%

Steps to reproduce:

1. clone https://github.com/janus-idp/backstage-plugins
2. run "yarn install"
3. Download the included diff file
4. run "git apply ~/Downloads/diff"
5. run "yarn start:backstage"
6. navigate to one of the orchestrator workflows

Actual results:
instead of the workflow viewer, a gray ractangle is shown
the network tab in the browser developer tools shows the error: "401 unauthorised" for request
http://localhost:7007/api/orchestrator/static/generated/envelope/serverless-workflow-combined-editor-envelope.html

Expected results:
workflow viewer loaded correctly