During the loop prepass the index variable is not fully constructed, so we can't rely it being negative
So we need to kiil the object type.

array.slice converts the native array to var array which was not captured during the optimization.
Due to that the native array type is forced to var array which leads to the type confusion.
Fixed this by killing the object type for the slice (as well as concat)

During GetChildren phase when we try to build JSON object we might throw exception. That skipped calling .Detach on the AutoPtr - which leads to release
the debugger property again.
Fixed that by catching and discarding the exception.