possible_exc_types checks for Uninferables

Fixes #998

pylint/extensions/_check_docs_utils.py

@@ -68,7 +68,8 @@ def possible_exc_types(node):
             handler = handler.parent
 
         if handler and handler.type:
-            excs = (exc.name for exc in astroid.unpack_infer(handler.type))
+            excs = astroid.unpack_infer(handler.type)
+            excs = (exc.name for exc in excs if exc is not astroid.Uninferable)
 
     excs = set(exc for exc in excs if not node_ignores_exception(node, exc))
     return excs

pylint/test/extensions/test_check_docs_utils.py

@@ -124,5 +124,18 @@ def my_func():
         expected = set(["RuntimeError", "ValueError"])
         self.assertEqual(found, expected)
 
+    def test_ignores_uninferable_type(self):
+        raise_node = astroid.extract_node('''
+        import not_a_module
+        def my_func():
+            try:
+                fake_func()
+            except not_a_module.Error:
+                raise #@
+        ''')
+        found = utils.possible_exc_types(raise_node)
+        expected = set()
+        self.assertEqual(found, expected)
+
 if __name__ == '__main__':
     unittest.main()