Function GDScriptFunctionState.isValid
Check whether the function call may be resumed. This is not the case if the function state was already resumed.
If extended_check is enabled, it also checks if the associated script and object still exist. The extended check is done in debug mode as part of GDScriptFunctionState, but you can use this if you know you may be trying to resume without knowing for sure the object and/or script have survived up to that point.
bool isValid
(
const(bool) extended_check = false
) nothrow @nogc const;