Crash when GC is triggered during script exception handling in StateChangeScript or ScriptAction

A crash occurs when a JavaScript exception is thrown inside a StateChangeScript or ScriptAction, and garbage collection is triggered during the exception handling process.

This can happen if the exception handling path allocates a new object, which in turn triggers a GC pass. During this GC run, the JS stack may contain invalid or stale values, leading to a crash.

Steps to Reproduce:

1. Extract and build the attached qt_gc_crash.zip project.

1. Run the application.

1. The application crashes during execution.

The issue appears specifically when a script defined in StateChangeScript or ScriptAction throws an exception and GC is triggered within the exception handler.

Expected Behavior:

The runtime should safely handle GC even if an exception is thrown inside the script, without leaving invalid values on the JS stack.

Actual Behavior:

The GC encounters invalid values on the JS stack, causing a crash.