              nlp = init_nlp(config, **init_kwargs)
              nlp.to_disk(init_path)
              msg.good(f"Saved initialized pipeline to {init_path}")
          else:
              nlp = util.load_model(init_path)
              if must_reinitialize(config, nlp.config):
                  msg.warn("Config has changed: need to re-initialize pipeline")
                  nlp = init_nlp(config, **init_kwargs)
                  nlp.to_disk(init_path)
                  msg.good(f"Re-initialized pipeline in {init_path}")
 
</s> remove     assert interpolated["corpora"]["train"]["path"] == ""
 </s> add     assert interpolated["corpora"]["train"]["path"] is None </s> remove train = ""
dev = ""
 </s> add train = null
dev = null </s> remove train = ""
dev = ""
 </s> add train = null
dev = null </s> remove train = ""
dev = ""
 </s> add train = null
dev = null
            nlp = util.load_model(init_path).from_config(config)
              nlp = init_nlp(config, **init_kwargs)
              nlp.to_disk(init_path)
              msg.good(f"Saved initialized pipeline to {init_path}")
          else:
            nlp = util.load_model(init_path).from_config(config)
              if must_reinitialize(config, nlp.config):
                  msg.warn("Config has changed: need to re-initialize pipeline")
                  nlp = init_nlp(config, **init_kwargs)
                  nlp.to_disk(init_path)
                  msg.good(f"Re-initialized pipeline in {init_path}")
keep keep keep keep replace keep keep keep keep keep
 Make corpus paths default to None and improve errors 
spacy/cli/train.py