This fixes a bug where `gc.collect()` would crash due to
emscripten_scan_stack being called synchronously within mp_js_do_str. The
fix is to make mp_js_do_str asynchronous.
Fixes#10692.
Signed-off-by: Eli Bierman <eli@elib.dev>
This changes the CustomEvent for stdout to use the existing `detail`
property of CustomEvent instead of adding a `data` property.
Signed-off-by: David Lechner <david@pybricks.com>