small sanity check

tensorpack/models/common.py

@@ -65,6 +65,7 @@ def layer_register(
     def wrapper(func):
         @wraps(func)
         def wrapped_func(*args, **kwargs):
+            assert args[0] is not None, args
             if use_scope:
                 name, inputs = args[0], args[1]
                 args = args[1:]  # actual positional args used to call func

tensorpack/train/config.py

@@ -81,6 +81,8 @@ class TrainConfig(object):
             assert_type(self.data, InputData)
             self.dataflow = None
 
+        if callbacks is None:
+            callbacks = []
         if isinstance(callbacks, Callbacks):
             # keep quiet now because I haven't determined the final API yet.
             log_deprecated(