These now works:
```
$ deno add @std/dotenv/load
$ deno add npm:preact/hooks
```
Previously we were erroring out, because this is a "package reference"
including
a subpath.
Closes https://github.com/denoland/deno/issues/25385
---------
Signed-off-by: Bartek Iwańczuk <biwanczuk@gmail.com>
Co-authored-by: David Sherret <dsherret@users.noreply.github.com>
Fixes #24607.
This PR makes the logic that caches top level dependencies (things
present in import map) smarter, so we handle JSR dependencies without
root exports.
