common.css does not exist
paver collect_static combines all the CSS files in 1 file. But the mxgraph javascript still tries to load common.css. This leads to a 404 error.
It's not really a problem, because the css is still present in the grapheditorxblock.css file, so functionally nothing changes. However, it does lead to problems in the console.
It also leads to The resource from “https://learn.staging.totem-project.org/static/xblock/resources/grapheditorxblock/public/css/common.css” was blocked due to MIME type (“text/html”) mismatch (X-Content-Type-Options: nosniff).e549e7b2ec0b4f4ba5d6992cfe0d8543 as reported in tutor-server#33 (closed)