I had a very similar issue which came down to Webstorm's type narrowing. I was using neverthrow in a Turbo monorepo. To fix, I had to direct WebStorm to my tsconfig base file.

1. Go to Settings -> languages & frameworks -> Typescript
2. add -p ./packages/typescript-config/base.json (or the location to your base tsconfig file) in the Options

With IntelliJ I found that often the idea gets confused and I need to either restart ide or invalidate cache...

Hope this helps anyone who was in the same boat as me