Need help from a C++ guru please

I have some of my code in Torque script (well most of it) and some of it in C++ for performance reasons. I should say that C++ is not my strongest language (much more comfortable with Java).

I'm having some random bugs which i've tracked down to my use of SimSet and iterators.

The basic problem is:

1. In C++ I'm iterating over a SimSet.
2. I call back into script to perform a script function on one of the iterated objects.
3. This call back results in the script side removing the object from the SimSet.
4. All is fine UNLESS the object which got removed happened to be at the END of the SimSet, then all hell breaks lose and TGBGame exits.

What I've found is that my iterator end pointer is pointing to the object removed from the SimSet and therefore the exit test in the loop never occurs.

I've fixed it (I hope) with a simple test at the end of the iterator loop but I thought that an iterator over a collection in C++ was a static collection and didn't change if the referenced objects were not longer in the collection?

This is my code with the fix:

Con::printf("********* START OF UPDATE *************");
		for(SimSet::iterator i = invaders->begin(); i != invaders->end(); ++i) {
			Con::printf("invaders end=%u", invaders->end());
			t2dSceneObject *invader = (t2dSceneObject *)(*i);
			if (invader != NULL) {
				bool isDead = dAtoi(invader->getDataField(StringTable->insert("isDead"), NULL));
				Con::printf("update invader i=%u, invader id=%u", i, invader->getId());					
				if (invader != NULL && Sim::findObject(invader->getId()) != NULL) {
					Con::printf("About to call updateInvader in TS");
					Con::executef(invader, 2, "updateInvader");
				}
				if (i == invaders->end()) {
					Con::printf("********* FOUND END - EXITING LOOP *************");
					break;
				}
				
			} // END if (invader != NULL)
		} // END for(SimSet::iterator i = invaders->begin(); i != invaders->end(); i++)
		
		Con::printf("********* END OF UPDATE *************");

Is there a more elegant way of dealing with this or am I barking up the wrong tree?
Cheers