map_elements + skip_nulls=False + pass_name=True PanicException when used with over

[cmdlineluser]

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 polars as pl

df = pl.DataFrame({"id": [1], "value": [2]})

df.select(
    pl.all().map_elements(lambda x: x, skip_nulls=False, pass_name=True)
      .over("id")
)
# thread 'polars-3' panicked at crates/polars-python/src/map/series.rs:228:19:
# python function failed AttributeError: 'list' object has no attribute 'alias'
# PanicException: python function failed AttributeError: 'list' object has no attribute 'alias'

Log output

No response

Issue description

(I have no valid use case for this, I was just trying to debug another skip_nulls issue and hit this.)

It seems when skip_nulls is False, the UDF gets given a plain Python list of values instead.

df = pl.DataFrame({"id": [1, 1, 2], "value": [2, 3, 4]})

df.select(
    pl.all().map_elements(lambda x: print(type(x), x), skip_nulls=False)
      .over("id")
)

# <class 'list'> [1, 1]
# <class 'list'> [2]
# <class 'list'> [2, 3]

With the default skip_nulls=True these are all Series objects.

Expected behavior

Series objects should still be given to UDF?

Installed versions

--------Version info---------
Polars:               1.8.2
Index type:           UInt32
Platform:             macOS-13.6.1-arm64-arm-64bit
Python:               3.12.2 (main, Feb  6 2024, 20:19:44) [Clang 15.0.0 (clang-1500.1.0.2.5)]

----Optional dependencies----
adbc_driver_manager:  <not installed>
cloudpickle:          <not installed>
connectorx:           <not installed>
deltalake:            <not installed>
fastexcel:            <not installed>
fsspec:               <not installed>
gevent:               <not installed>
great_tables:         <not installed>
hvplot:               <not installed>
matplotlib:           <not installed>
nest_asyncio:         <not installed>
numpy:                1.26.4
openpyxl:             <not installed>
pandas:               2.2.1
pyarrow:              15.0.2
pydantic:             <not installed>
pyiceberg:            <not installed>
sqlalchemy:           <not installed>
torch:                <not installed>
xlsx2csv:             <not installed>
xlsxwriter:           <not installed>