This is short example about Observables and how they can be really evil.
Fortunately we have a hero called [Object.freeze(obj)](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze?redirectlocale=en-US&redirectslug=JavaScript%2FReference%2FGlobal_Objects%2FObject%2Ffreeze).
TLDR; Think about when Web Workers make sense and when not. It's tempting to run something on the background, but not always. This is the story of what I did wrong.