LazyFrame sort and slice with nulls_last causes panic

[daviskirk]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

pl.LazyFrame({"a": [None, 1.2]}).sort("a", nulls_last=True).slice(0, 10).collect()

Log output

thread '<unnamed>' panicked at crates/polars-core/src/chunked_array/ops/sort/arg_sort.rs:83:23:
range end index 9 out of range for slice of length 1
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
---------------------------------------------------------------------------
PanicException                            Traceback (most recent call last)
Cell In[2], line 1
----> 1 pl.LazyFrame({"a": [None, 1.2]}).sort("a", nulls_last=True).slice(0, 10).collect()

File polars/lazyframe/frame.py:2029, in LazyFrame.collect(self, type_coercion, predicate_pushdown, projection_pushdown, simplify_expression, slice_pushdown, comm_subplan_elim, comm_subexpr_elim, cluster_with_columns, collapse_joins, no_optimization, streaming, engine, background, _eager, **_kwargs)
   2027 # Only for testing purposes
   2028 callback = _kwargs.get("post_opt_callback", callback)
-> 2029 return wrap_df(ldf.collect(callback))

PanicException: range end index 9 out of range for slice of length 1

Issue description

Sorting and then slicing when using nulls_last, causes polars to panic.

The panic does not occur when:

• nulls_last is not set
• no nulls are in the sort column
• we collect before slicing
• setting maintain_order=True flag

Expected behavior

No panic should occur and the result should be the same as for collected dataframes.

Installed versions

--------Version info---------
Polars:              1.15.0
Index type:          UInt32
Platform:            Linux-6.8.0-49-generic-x86_64-with-glibc2.39
Python:              3.11.9 (main, Apr 19 2024, 16:48:06) [GCC 11.2.0]
LTS CPU:             False

----Optional dependencies----
adbc_driver_manager  <not installed>
altair               <not installed>
boto3                <not installed>
cloudpickle          <not installed>
connectorx           <not installed>
deltalake            <not installed>
fastexcel            <not installed>
fsspec               2024.3.1
gevent               <not installed>
google.auth          2.29.0
great_tables         <not installed>
matplotlib           <not installed>
nest_asyncio         <not installed>
numpy                1.24.3
openpyxl             3.1.2
pandas               2.1.4
pyarrow              16.0.0
pydantic             1.10.13
pyiceberg            <not installed>
sqlalchemy           1.4.39
torch                <not installed>
xlsx2csv             <not installed>
xlsxwriter           <not installed>