Fix PyTorch BiLSTM

spacy/_ml.py

@@ -29,6 +29,7 @@ from . import util
 
 try:
     import torch.nn
+    from thinc.extra.wrappers import PyTorchWrapperRNN
 except:
     torch = None
 
@@ -252,7 +253,7 @@ def link_vectors_to_models(vocab):
 
 def PyTorchBiLSTM(nO, nI, depth, dropout=0.2):
     if depth == 0:
-        return noop()
+        return layerize(noop())
     model = torch.nn.LSTM(nI, nO//2, depth, bidirectional=True, dropout=dropout)
     return with_square_sequences(PyTorchWrapperRNN(model))
 
@@ -299,7 +300,6 @@ def Tok2Vec(width, embed_size, **kwargs):
             ExtractWindow(nW=1)
             >> LN(Maxout(width, width*3, pieces=cnn_maxout_pieces))
         )
-
         tok2vec = (
             FeatureExtracter(cols)
             >> with_flatten(