refactor: Resolve circular dependencies

[treppo]

The build with Rollup was complaining about circular file dependencies. This commit fixes those.

[johnholdun]

Thanks for your contribution! Unfortunately I still see circular dependency warnings with this PR, and there are some changes in there that seem unrelated to the warning whose intentions I don't totally understand. I'm going to close this, but if you'd like to open a new PR with the other changes (or try to track down the remaining circular dependencies), please feel free. Thanks again!