init default_command to None, which leads to better errors
@@ -72,7 +72,7 @@ class Experiment(Ingredient):
ingredients=ingredients,
interactive=interactive,
_caller_globals=caller_globals)
- self.default_command = ""
+ self.default_command = None
self.command(print_config, unobserved=True)
self.command(print_dependencies, unobserved=True)
self.command(save_config, unobserved=True)
