Note:

The root cause of this issue lies in uv_venv_auto attempting to resolve the path to uv, which introduces a cyclic dependency:

toolset → ($npm/go dep env) → config → (uv path) → toolset

This cycle leads to a deadlock in LazyLock or OnceCell due to reentrant initialisation, where an item tries to access itself during its own initialisation.

Ideally, the correct fix would involve resolving the reentrancy issue directly.
However, since that seems complex, I'm trying to workaround by bypassing LazyLock or OnceCell during their initialization phase.
It means returning None or default values instead of trying to init, thus avoiding the deadlock.

@jdx I apologise for taking so long to fix my PR.
I confirmed this fixes the deadlock for npm or go backends with uv_venv_auto.

The test seems to fail because of cargo-insta installation.