[FIX] pylint_odoo: Fix IndexError corner case

Running pylint for many files it raised an IndexError fixed here

src/pylint_odoo/checkers/odoo_addons.py

@@ -1585,7 +1585,10 @@ def get_odoo_models_class(self, node):
                 break
             if not isinstance(attr, nodes.Name):
                 continue
-            imported_class = node.lookup(attr.name)[1][-1]
+            imported_class = node.lookup(attr.name)[1]
+            if not imported_class:
+                continue
+            imported_class = imported_class[-1]
             package_names = []
             if isinstance(imported_class, nodes.ImportFrom):
                 package_names = imported_class.modname.split(".")[:1]

testing/resources/test_repo/broken_module/models/broken_model.py

@@ -850,3 +850,11 @@ class NoOdoo(object):
     ]
     for query in queries:
         self.env.cr.execute(query)
+
+class Ccc(object):
+
+    class Ddd(object):
+        pass
+
+    class Eee(Ddd):
+        pass