Update t2s_model.py (#1283)

y is None at no reference mode, and Nonetype object has no attribute shape

GPT_SoVITS/AR/models/t2s_model.py

@@ -528,6 +528,7 @@ class Text2SemanticDecoder(nn.Module):
             y_pos = None
             xy_pos = x
             y = torch.zeros(x.shape[0], 0, dtype=torch.int, device=x.device)
+            prompts = y
             ref_free = True
 
         x_attn_mask_pad = F.pad(
@@ -582,4 +583,4 @@ class Text2SemanticDecoder(nn.Module):
 
         if ref_free:
             return y[:, :-1], 0
-        return y[:, :-1], idx - 1
+        return y[:, :-1], idx - 1