quick fix

app/corpora/cqi/models/attributes.py

@@ -140,7 +140,7 @@ class StructuralAttribute(Attribute):
             rc_rbound = \
                 self.cpos_by_id(min((last_id + context), (self.size - 1)))[1]
             if rc_rbound != last_cpos:
-                rc_lbound = min((last_cpos + 1), (self.size - 1))
+                rc_lbound = min((last_cpos + 1), (self.corpus.size - 1))
                 rc = (rc_lbound, rc_rbound)
                 cpos_list_rbound = rc_rbound
             else: