fix some bugs

timm/models/twins.py

@@ -294,9 +294,9 @@ class Twins(nn.Module):
         self.F4=F4
         self.extra_norm = extra_norm
         self.strides = strides
+        self.norm_list = nn.ModuleList()
         if self.task == 'seg':
             if self.extra_norm:
-                self.norm_list = nn.ModuleList()
                 for dim in embed_dims:
                     self.norm_list.append(norm_layer(dim))
 
@@ -311,6 +311,8 @@ class Twins(nn.Module):
                         self.patch_embeds.append(
                             PatchEmbed(img_size // patch_size // s, strides[i-1], embed_dims[i - 1], embed_dims[i]))
                     s = s * strides[i-1]        
+        if self.task == 'cls':
+            del self.norm_list
 
         self.blocks = nn.ModuleList()
         dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))]  # stochastic depth decay rule