We should not call into an instance which is suspended, since that would introduce a second stack and control flow. We can determine if an instance is suspended by Qt using the "resume" field which holds the resume function. It is however not possible to determine if an instance is suspended in general, for instance if it has called emscripten_sleep(). Instead, assume that we can never call into the instance if asyncify/jspi is enabled, and make resuming the instance the only way to process events. This breaks support for returning control to the browser (e.g. by not calling app->exec()) when asyncify is enabled, which is unfortunate. When using asyncify exec() must be called to begin event processng. Fixes: QTBUG-137519 Pick-to: 6.10 Change-Id: Id8356f7fda624263fd3840f747370b23860738ab Reviewed-by: Piotr Wierciński <piotr.wiercinski@qt.io>