Fix unit test

TTS/vocoder/models/gan.py

@@ -155,6 +155,7 @@ class GAN(BaseVocoder):
 
         if optimizer_idx == 1:
             # GENERATOR loss
+            scores_fake, feats_fake, feats_real = None, None, None
             if self.train_disc:
                 if len(signature(self.model_d.forward).parameters) == 2:
                     D_out_fake = self.model_d(self.y_hat_g, x)
@@ -182,7 +183,6 @@ class GAN(BaseVocoder):
                 self.y_hat_g, y, scores_fake, feats_fake, feats_real, self.y_hat_sub, self.y_sub_g
             )
             outputs = {"model_outputs": self.y_hat_g}
-
         return outputs, loss_dict
 
     @staticmethod
@@ -216,6 +216,7 @@ class GAN(BaseVocoder):
     @torch.no_grad()
     def eval_step(self, batch: Dict, criterion: nn.Module, optimizer_idx: int) -> Tuple[Dict, Dict]:
         """Call `train_step()` with `no_grad()`"""
+        self.train_disc = True  # Avoid a bug in the Training with the missing discriminator loss
         return self.train_step(batch, criterion, optimizer_idx)
 
     def eval_log(