Fixed concept token parsing

tests/core/test_utils.py

@@ -158,6 +158,7 @@ def test_i_can_escape():
     ("c:key|id:", "key", "id"),
     ("c:|id:", None, "id"),
     ("c:key|:", "key", None),
+    ("c:key|id:x", None, None),
 ])
 def test_i_can_unstr_concept(text, expected_key, expected_id):
     k, i = core.utils.unstr_concept(text)