Gem doesn't seem to be available

When running any Gem related example I get the following error:

>error: couldn't create "gemwin"

I think Gem is compiled by looking at the manifest, but doesn't seem to be available

Reproduce the error by running any Gem-related example, then inspect how Gem is represented in the manifest and how the example attempts to create "gemwin". Done means identifying why Gem is unavailable and confirming that the affected examples run without this error.

Written by the indexing model from the issue text.