fix: direct LightningMusicgen instantiation, not params.instantiate()

app.py

@@ -75,7 +75,8 @@ def build_params(encodec_weights: str, lm_weights: str) -> hp.MusicgenParams:
 
 def load_checkpoint(params: hp.MusicgenParams, ckp_path: str) -> LightningMusicgen:
     """Instantiate model from params and load fine-tuned checkpoint onto CPU."""
-    model: LightningMusicgen = params.instantiate()
+    model = LightningMusicgen(params)   # direct instantiation bcs params.instantiate() uses 
+                                        # pydoc.locate("stage.*") which fails after flattening
     sft.load_model(model, ckp_path)
     return model.cpu().eval()