- type-only files never get processed by Rollup as their imports are
  elided/removed by TS in the resulting compiled JS file
  - so, as a workaround, make sure that all files in the `tsconfig`
    `include` (i.e. in `parsedConfig.fileNames`) are also type-checked
    - note that this will not catch _all_ type-only imports, in
      particular if one is using `tsconfig` `files` (or in general _not_
      using glob patterns in `include`) -- this is just a workaround,
      that requires a separate fix
  - we do the same process for generating declarations for "missed"
    files right now in `_onwrite`, so basically do the same thing but
    for type-checking in `_ongenerate`

(_technically_ speaking, there could be full TS files
(i.e. _not_ type-only) that are in the `include` and weren't
transformed
- these would basically be independent TS files not part of the bundle
  that the user wanted type-checking and declarations for (as we
  _already_ generate declarations for those files))

- `buildEnd` is a more correct place for it, since this does not generate any output files
  - (unlike the missed declarations)
  - and this means it's only called once per build, vs. once per output

- remove the check against the `declarations` dict as one can type-check without outputting declarations
  - i.e. if `declaration: false`; not the most common use-case for rpt2, but it is one

- since `parsedConfig.fileNames` could include files that were already checked during the `transform` hook
- and because `declarations` dict is empty when `declaration: false`, so can't check against that

- because printing diagnostics can bail if the category was error
  - that can result in a file being type-checked but not added to checkedFiles

…rateBundle

- per ezolenko, the whole generateRound etc stuff was a workaround because the buildEnd hook actually _didn't exist_ before
  - so now that it does, we can use it to simplify some logic
  - no longer need `_ongenerate` as that should be in `buildEnd`, and no longer need `_onwrite` as it is the only thing called in `generateBundle`, so just combine them
  - importantly, `buildEnd` also occurs before output generation, so this ensures that type-checking still occurs even if `bundle.generate()` is not called

- also move the `walkTree` call to above the "missed" type-checking as it needs to come first
  - it does unconditional type-checking once per watch cycle, whereas "missed" only type-checks those that were, well, "missed"
  - so in order to not have duplication, make "missed" come after, when the `checkedFiles` Set has been filled by `walkTree` already

- and for simplification, just return early on error to match the current behavior
  - in the future, may want to print the error and continue type-checking other files
    - so that all type-check errors are reported, not just the first one

NOTE: this is WIP because the `cache.done()` call and the `!noErrors` message are incorrectly blocked behind the `pluginOptions.check` conditional right now
- `cache.done()` needs to be called regardless of check or error or not, i.e. in all scenarios
  - but ideally it should be called after all the type-checking here
- `!noErrors` should be logged regardless of check or not
  - and similarly, after the type-checking

- instead of making a big `if` statement, decided to split out a `buildDone` function
  - to always call at the end of the input phase

- we can also move the `cache().done()` in `emitSkipped` into `buildEnd`, as `buildEnd` gets called when an error occurs as well
  - and this way we properly print for errors as well

- `buildDone` will have more usage in other PRs as well, so I figure it makes sense to split it out now as well

- i.e. bail out when `abortOnError: true`, which `ConsoleContext` can't do
  - `ConsoleContext` is basically meant for everywhere `RollupContext` can't be used
    - which is effectively only in the `options` hook, per the Rollup docs: https://rollupjs.org/guide/en/#options

- now that the integration tests exist, we can actually test this scenario

- refactor: give each test their own `onwarn` mock when necessary
  - while `restoreMocks` is set in the `jest.config.js`, Jest apparently has poor isolation of mocks: jestjs/jest#7136
    - if two tests ran in parallel, `onwarn` was getting results from both, screwing up the `toBeCalledTimes` number
  - couldn't get the syntax error to work with `toBeCalledTimes` either
    - if no mock is given, it _does_ print warnings, but if a mock is given, it doesn't print, yet isn't called?
      - I think the mock is getting screwed up by the error being thrown here; maybe improperly saved or something