OnScriptDestroyed should not be called when Tundra is exiting

[Stinkfist0]

When Tundra Application/Framework is exiting, most of the core API pointers/dynamic objects are garbage which results in error prints in many scripts: Error: In script destructor: Error: cannot access member IsRunning of deleted QObject

In this particular case server was tried to be queried.

[cadaver]

Could also destroy all script instances (if possible) before the core objects.

[jonnenauha]

I think this should be automatically solved with the TundraProtocolModule disconnect. At this point the scene should be reseted an all scripts destroyed. However the dtor disconnect is too late for a shutdown. As some modules (APIs I think persist untill modules are unloaded) might already be freed.

Imo this is related to #665

[Stinkfist0]

Well, these error happens also when running scene only locally. But yes, both issues are related to application teardown in some way.

[cadaver]

The question is also, whether shutdown should be, from the perspective of scripts, same as the scene being emptied of all objects. That's naturally the internal end result anyway (as scene must be cleared before it can be properly deleted) but there could also be a separate script callback for shutdown (like OnFrameworkExit or something)

However, having a separate callback, or extra logic to suppress OnScriptDestroyed makes the code more complex. The simplest solution is a well-defined teardown order.