Fixes: #132422, #133288.
`ED_area_init()` is called when the editor in an area changes, this also changes
the available regions. That means, region polling needs to be executed. The
crash was happening because that wasn't the case, and the asset shelf region was
initialized before the polling was executed, which allocates region data in the
`on_poll_success()` callback.
Also had to pass context to `ED_area_init()`, which is an annoyance, but should
be fine. Similar functions like `ED_area_exit()` take it too.
Pull Request: https://projects.blender.org/blender/blender/pulls/133388
efadb938f0