fix: make DOS from other agents impossible

There were some missing value checks. Other agents could cause errors in the User Interrupt agent or the Program Manager agent by sending malformed messages.

ref: N25B-453

src/control_backend/agents/user_interrupt/user_interrupt_agent.py

@@ -335,6 +335,8 @@ class UserInterruptAgent(BaseAgent):
             belief_name = f"force_{asl}"
         else:
             self.logger.warning("Tried to send belief with unknown type")
+            return
+
         belief = Belief(name=belief_name, arguments=None)
         self.logger.debug(f"Sending belief to BDI Core: {belief_name}")
         # Conditional norms are unachieved by removing the belief