How to debug nuxt.js "yarn dev" when it just stops loading?

Question

Today one of our nuxt.js products just stopped loading when you start it. There is no error. The browswer never loads. No log.

What we have tried:

• move to a different port, like 57836 - Same
• Try different branches, rollback to known working state - same problem
• Try a different nuxt porject. The other project loads fine
• Load the _tailwind view, works find
• Delete the whole project, pull it down again from git and yarn install - Same problem
• run Yarn upgrade, a few things updated, but still the same problem
• Try to load it from a http client like postman, same thing no response
• Try loading in different browsers - same problem

So my question, how do I even start debugging this? How to I see requests to the build in server?