[lib] CLUnfolder: fix exception handling when text properties/events have a bad syntax

library/cadbiom/models/clause_constraints/mcl/CLUnfolder.py

@@ -1133,6 +1133,12 @@ class CLUnfolder(object):
             self.dynamic_system.symb_tab,
             self.dynamic_system.report
         )
+        if tree_prop is None:
+            raise MCLException(
+                "error during parsing of '%s', please check the property syntax"
+                % property_text
+            )
+
         # Avoid name collisions of aux var
         prop_visitor = CLPropertyVisitor(self.__lit_cpt)
         tree_prop.accept(prop_visitor)
@@ -1165,6 +1171,12 @@ class CLUnfolder(object):
             True, # Collect free clocks (events)
             self.dynamic_system.report
         )
+        if tree_prop is None:
+            raise MCLException(
+                "error during parsing of '%s', please check the event syntax"
+                % property_text
+            )
+
         # Avoid name collisions of aux var
         prop_visitor = CLPropertyVisitor(self.__lit_cpt)
         tree_prop.accept(prop_visitor)