fix(pyramid/predicates): avoid to show an error without a session connection

* Related to issue #335

cubicweb/pyramid/predicates.py

@@ -59,6 +59,9 @@ class MatchIsEIDPredicate(object):
         except ValueError:
             return False
 
+        if request.cw_cnx is None:
+            return False
+
         try:
             request.cw_cnx.entity_from_eid(eid)
         except UnknownEid:
@@ -85,6 +88,9 @@ class MatchIsETypeAndEIDPredicate(object):
         except ValueError:
             return False
 
+        if request.cw_cnx is None:
+            return False
+
         try:
             entity = request.cw_cnx.entity_from_eid(eid)
         except UnknownEid:
@@ -115,6 +121,9 @@ class HasCWPermissionRoutePredicate:
         if not eid:
             return False
 
+        if request.cw_cnx is None:
+            return False
+
         try:
             entity = request.cw_cnx.entity_from_eid(eid)
         except UnknownEid: