schema: use parsed object only if available

With libyang/sysrepo 4 and printed contexts, the parsed object can be
null.
Check the parsed object before using it to get the node type.

Fixes: 0a4b09f ("cffi: allows to usage of libyang v4")
Signed-off-by: Jeremie Leska <jeremie.leska@6wind.com>

Author: jeremie6wind

libyang/schema.py

@@ -1568,6 +1568,8 @@ def units(self) -> Optional[str]:
         return c2str(self.cdata_leaf.units)
 
     def type(self) -> Type:
+        if not self.cdata_leaf_parsed:
+            return Type(self.context, self.cdata_leaf.type, None)
         return Type(self.context, self.cdata_leaf.type, self.cdata_leaf_parsed.type)
 
     def is_key(self) -> bool:
@@ -1599,6 +1601,8 @@ def units(self) -> Optional[str]:
         return c2str(self.cdata_leaflist.units)
 
     def type(self) -> Type:
+        if not self.cdata_leaflist_parsed:
+            return Type(self.context, self.cdata_leaflist.type, None)
         return Type(
             self.context, self.cdata_leaflist.type, self.cdata_leaflist_parsed.type
         )