Fix CalledProcessError

✅ Solution

The "CalledProcessError" in vllm often arises during installation or runtime due to missing or incorrectly compiled dependencies, particularly when using custom or CPU backends. Ensure all necessary system dependencies are installed as specified in the vllm documentation and that any custom kernels or CUDA extensions are built correctly with the appropriate compiler and flags for your environment. Rerunning the installation with verbose logging (`pip install -vvv .`) can help pinpoint the exact failed command and missing dependency.