- previously, the `checkImports` flag was set to `true` for type-checking, but `false` for compilation
  - I _believe_ it is `false` because the compiled JS shouldn't change if an import changes
    - though I'm not sure if that was the original intent behind the code
  - problematically though, compilation results can include declarations, and those _can_ change if imports change
    - for instance, the types of an import can change the declaration that is output
  - so now, only set it to `false` for compilation if declarations are _not_ needed

- ezolenko gave a good example of enums, which can indeed cause the compiled JS code to change based on imports
  - so also check `!isolatedModules` as well
  - I thought it might be the case that the code wouldn't handle other edge cases, but couldn't think of one off the top of my head
    - ironically, I compared it to Babel, which transpiles per file, and Babel _requires_ `isolatedModules` to work