assertion added avoiding setProblem to non-key frames

src/frame/frame_base.cpp

@@ -303,12 +303,13 @@ void FrameBase::link(TrajectoryBasePtr _trj_ptr)
 
 void FrameBase::setProblem(ProblemPtr _problem)
 {
+    assert(isKey() && "Trying to setProblem to a non keyframe");
+
     if (_problem == nullptr || _problem == this->getProblem())
         return;
 
     NodeBase::setProblem(_problem);
-    if (this->isKey())
-        registerNewStateBlocks(_problem);
+    registerNewStateBlocks(_problem);
 
     for (auto cap : capture_list_)
         cap->setProblem(_problem);