[FixBug] Improve exception string in `tensorizer.py` (#31680)

Signed-off-by: maang <maang_h@163.com>
Signed-off-by: maang-h <55082429+maang-h@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

vllm/model_executor/model_loader/tensorizer.py

@@ -764,7 +764,10 @@ def tensorize_lora_adapter(lora_path: str, tensorizer_config: TensorizerConfig):
     elif tensor_path.endswith(".bin"):
         tensors = torch.load(tensor_path, weights_only=True)
     else:
-        raise ValueError("Unsupported file: %s", tensor_path)
+        raise ValueError(
+            f"Unsupported adapter model file: {tensor_path}. "
+            f"Must be a .safetensors or .bin file."
+        )
 
     with open(config_path) as f:
         config = json.load(f)