scan_parquet + with_row_index + selecting only the index returns empty dataframe

[guyrosin]

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

import tempfile
from pathlib import Path

import polars as pl

with tempfile.TemporaryDirectory() as d:
    path = Path(d) / "test.parquet"
    pl.DataFrame({"A": [1, 4], "B": [2, 5]}).write_parquet(path)
    df = pl.scan_parquet(path).with_row_index()

    print(df.collect().select("index"))  # OK
    print(df.select("index", "A").collect())  # OK

    print(df.select("index").collect())  # empty

Output:

shape: (2, 1)
┌───────┐
│ index │
│ ---   │
│ u32   │
╞═══════╡
│ 0     │
│ 1     │
└───────┘
shape: (2, 2)
┌───────┬─────┐
│ index ┆ A   │
│ ---   ┆ --- │
│ u32   ┆ i64 │
╞═══════╪═════╡
│ 0     ┆ 1   │
│ 1     ┆ 4   │
└───────┴─────┘
shape: (0, 1)
┌───────┐
│ index │
│ ---   │
│ u32   │
╞═══════╡
└───────┘

Log output

No response

Issue description

The index column cannot be selected alone after a scan_parquet operation.
This behavior doesn't occur for scan_csv.

Expected behavior

The index column should be returned, as it does for a DataFrame

Installed versions

--------Version info---------
Polars:              1.6.0
Index type:          UInt32
Platform:            Linux-6.5.0-1024-aws-x86_64-with-glibc2.35
Python:              3.11.9 (main, Jul 13 2024, 23:44:43) [Clang 17.0.6 ]

----Optional dependencies----
adbc_driver_manager  <not installed>
altair               5.4.1
cloudpickle          3.0.0
connectorx           <not installed>
deltalake            <not installed>
fastexcel            0.11.6
fsspec               2024.6.1
gevent               <not installed>
great_tables         <not installed>
matplotlib           3.9.2
nest_asyncio         1.6.0
numpy                1.26.4
openpyxl             <not installed>
pandas               2.2.2
pyarrow              17.0.0
pydantic             2.8.2
pyiceberg            <not installed>
sqlalchemy           2.0.32
torch                2.2.2+cu121
xlsx2csv             0.8.3
xlsxwriter           <not installed>