Calling list_indices results in "v2 format has no concept of row groups"

From Discord (kohlerbear):

Calling list_indices results in the following error:

>>> a=d.list_indices()
thread '<unnamed>' panicked at /home/runner/work/lance/lance/rust/lance-index/src/scalar/lance_format.rs:154:9:
not implemented: v2 format has no concept of row groups
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/root/.local/lib/python3.10/site-packages/lance/dataset.py", line 221, in list_indices
    return self._ds.load_indices()
pyo3_runtime.PanicException: not implemented: v2 format has no concept of row groups

Any guidance on how to further debug this? This is on lancedb 0.24.3.

What I'm ultimately interested in: I'd like to understand my scalar index stats. I had a script I was using to enumerate index names, but I can also just use a direct call to dataset.stats.index_stats(). That results in a different error:

>>> print(d.stats.index_stats("occlusion_idx")["num_unindexed_rows"])
...
thread 'lance_background_thread' panicked at /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/arrow-data-52.2.0/src/transform/utils.rs:42:56:
offset overflow
thread '<unnamed>' panicked at /home/runner/work/lance/lance/rust/lance-encoding/src/decoder.rs:1361:65:
called Result::unwrap() on an Err value: JoinError::Panic(Id(578), "offset overflow", ...)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/root/.local/lib/python3.10/site-packages/lance/dataset.py", line 2922, in index_stats
    index_stats = json.loads(self._ds.index_statistics(index_name))
pyo3_runtime.PanicException: called Result::unwrap() on an Err` value: JoinError::Panic(Id(578), "offset overflow", ...)

Start with rust/lance-index/src/scalar/lance_format.rs:154 and the Python entry points Dataset.list_indices and stats.index_stats. Reproduce both reported failures on lancedb 0.24.3, then trace the v2 format and index-statistics paths; done means listing indices and retrieving scalar index statistics no longer panic.