schema: handle None parsed objects in type creation

In libyang4, when dealing with printed contexts, the parsed object can
be None.
Check it 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

@@ -1568,7 +1568,11 @@ def units(self) -> Optional[str]:
         return c2str(self.cdata_leaf.units)
 
     def type(self) -> Type:
-        return Type(self.context, self.cdata_leaf.type, self.cdata_leaf_parsed.type)
+        return Type(
+            self.context,
+            self.cdata_leaf.type,
+            self.cdata_leaf_parsed.type if self.cdata_leaf_parsed else None,
+        )
 
     def is_key(self) -> bool:
         if self.cdata_leaf.flags & lib.LYS_KEY:
@@ -1600,7 +1604,9 @@ def units(self) -> Optional[str]:
 
     def type(self) -> Type:
         return Type(
-            self.context, self.cdata_leaflist.type, self.cdata_leaflist_parsed.type
+            self.context,
+            self.cdata_leaflist.type,
+            self.cdata_leaflist_parsed.type if self.cdata_leaflist_parsed else None,
         )
 
     def defaults(self) -> Iterator[Union[None, bool, int, str, float]]: