[Installation]: Gemma2 Installing Flash Infer `[rank0]: TypeError: 'NoneType' object is not callable`

The source of your error is that you have installed the wrong version of FlashInfer.

FlashInfer builds wheels for specific torch and cuda versions. vLLM v0.5.1 uses `torch==2.3` and `cuda==12.1`. So you will likely want to download the following wheel:

```bash
pip install flashinfer -i https://flashinfer.ai/whl/cu121/torch2.3
```