No error handling when adding a WorkerRun that would result in a cycle

Sentry Issue: ARKINDEX-FRONTEND-138

Error: Request failed with status code 400
  at createError (./node_modules/axios/lib/core/createError.js:16:15)
  at settle (./node_modules/axios/lib/core/settle.js:17:12)
  at apply (./node_modules/axios/lib/adapters/xhr.js:61:7)
  at r (./node_modules/@sentry/browser/esm/helpers.js:71:23)

Not only should the frontend be able to handle errors, it might be able to detect the cycles itself too.