fix: Don't oob on nulls in list.get

[ritchie46]

fixes #17252

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.88%. Comparing base (cdfeb4f) to head (45aaa44).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #17262   +/-   ##
=======================================
  Coverage   80.87%   80.88%           
=======================================
  Files        1470     1470           
  Lines      192631   192640    +9     
  Branches     2750     2750           
=======================================
+ Hits       155796   155814   +18     
+ Misses      36327    36318    -9     
  Partials      508      508           

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[mcrumiller]

@ritchie46 I think you missed the case where index is an column (https://github.com/pola-rs/polars/blob/main/crates/polars-plan/src/dsl/function_expr/list.rs#L426-L456):

s = pl.Series("a", [None, [1]], dtype=pl.List(pl.Int32))

# OK; fixed in PR
s.list.get(0, null_on_oob=False)

# not fixed in PR
df = pl.DataFrame({
    "a": s,
    "ind": [0, 0]
})
df.select(pl.col("a").list.get("ind", null_on_oob=False))
# polars.exceptions.ComputeError: get index is out of bounds