Fix ErrorsWithCodes().__class__ return value

spacy/errors.py

@@ -7,8 +7,11 @@ def add_codes(err_cls):
 
     class ErrorsWithCodes(object):
         def __getattribute__(self, code):
-            msg = getattr(err_cls, code)
+            if not code.startswith('__'):
-            return "[{code}] {msg}".format(code=code, msg=msg)
+                msg = getattr(err_cls, code)
+                return "[{code}] {msg}".format(code=code, msg=msg)
+            else:
+                return super().__getattribute__(code)
 
     return ErrorsWithCodes()
 

spacy/tests/test_errors.py

@@ -0,0 +1,13 @@
+from inspect import isclass
+
+from spacy.errors import add_codes
+
+
+@add_codes
+class Errors(object):
+    E001 = "error description"
+
+
+def test_add_codes():
+    assert Errors.E001 == "[E001] error description"
+    assert isclass(Errors.__class__)