changed masking such that it works also if belief state has less keys then default state

convlab/policy/vector/vector_base.py

@@ -259,11 +259,12 @@ class VectorBase(Vector):
             if intent in ['nobook', 'nooffer'] and slot != 'none':
                 mask_list[i] = 1.0
 
-            if "book" in slot and intent == 'inform' and not self.state[domain][slot]:
+            if "book" in slot and intent == 'inform':
+                if not self.state.get(domain, {}).get(slot, {}):
                     mask_list[i] = 1.0
 
             if domain == 'taxi':
-                if slot in self.state['taxi']:
+                if slot in self.state.get('taxi', {}):
                     if not self.state['taxi'][slot] and intent == 'inform':
                         mask_list[i] = 1.0