[Type] ndarray typing 2: Fix NDArray single-arg subscript crash

[hughperkins]

NdarrayType.class_getitem crashed when called with a single arg (e.g. NdarrayType[dtype]) because it tried to unpack a non-tuple. Wrap single args in a tuple before passing to init.

Issue: #

Brief Summary

copilot:summary

Walkthrough

copilot:walkthrough

[hughperkins]

Opus 4.6 review:

PR Review: hp/typing-t4-2-ndarray-subscript

Summary

This PR fixes NdarrayType.__class_getitem__ to correctly handle single-argument subscript notation (e.g. NdarrayType[qd.i32]). Python's subscript protocol passes a single value directly (not a tuple) when there is one item, so the change normalizes args to a tuple before unpacking. It also removes the unused **kwargs parameter.

Issues Found

No issues found. The change is correct and all 190 ndarray-related tests pass.

Suggestions for Improvement

1. Add a test for single-argument subscript — The codebase uses NDArray[dtype, ndim] extensively but I found no tests for NDArray[dtype] (dtype-only). Consider adding a test in test_ndarray_typing.py:

   def test_ndarray_typing_single_arg():
       t = qd.types.NDArray[qd.i32]
       assert t.dtype == qd.i32
       assert t.ndim is None

2. Optional: handle NdarrayType[] explicitly — NdarrayType[()] works (empty tuple → cls()), but NdarrayType[] is invalid Python syntax. No change needed; this is just for awareness.

3. Style — The implementation is consistent with the codebase. The tuple normalization pattern is a common idiom for __class_getitem__ (e.g. similar to typing.Generic).