add more asserts to onNewSolution

Strictly speaking there is no need for the invariant,
but if something violates it a stage computed something it wasn't meant to.

Author: v4hn

core/src/container.cpp

@@ -353,7 +353,13 @@ inline void updateStatePrios(const SolutionSequence::container_type& partial_sol
 }
 
 void SerialContainer::onNewSolution(const SolutionBase& current) {
+	// failures should never trigger this callback
 	assert(!current.isFailure());
+
+	// states of solution must be active, otherwise this would not have been computed
+	assert(current.start()->priority().enabled());
+	assert(current.end()->priority().enabled());
+
 	auto impl = pimpl();
 	const Stage* creator = current.creator();
 	auto& children = impl->children();