Apply suggestions from code review

fix some bugs in merge_lora

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

model/model_lora.py

@@ -47,12 +47,15 @@ def merge_lora(model, path):
     state_dict = {(k[7:] if k.startswith('module.') else k): v for k, v in state_dict.items()}
 
     for name, module in model.named_modules():
-        if isinstance(module, nn.Linear):
+        if isinstance(module, nn.Linear) and module.weight.shape[0] == module.weight.shape[1]:
             key_A = f"{name}.lora.A.weight"
             key_B = f"{name}.lora.B.weight"
             if key_A in state_dict and key_B in state_dict:
                 # 直接合并权重: W_new = W_old + B @ A
-                module.weight.data += state_dict[key_B] @ state_dict[key_A]
+                device = module.weight.device
+                A_weight = state_dict[key_A].to(device)
+                B_weight = state_dict[key_B].to(device)
+                module.weight.data += B_weight @ A_weight
                 
     return model