[C++][Python] Not providing a sort_key in the "select_k_unstable" kernel crashes #29603
Description
The new kernel added in ARROW-1565 crashes in Python if you don't specify a sort_key:
In [1]: import pyarrow.compute as pc
In [2]: arr = pa.array([1, 2, 3, 4])
In [3]: pc.select_k_unstable(arr, k=2)
Segmentation fault (core dumped)cc @aocsa
Reporter: Joris Van den Bossche / @jorisvandenbossche
Assignee: Alexander Ocsa / @aocsa
PRs and other links:
Note: This issue was originally created as ARROW-14003. Please see the migration documentation for further details.