BUG: ArrowEA._cast_pointwise_result([Decimal(NaN)])

[jbrockmendel]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd
from decimal import Decimal

ser = pd.Series([], dtype="float64[pyarrow]")
arr = ser.array
item = Decimal("NaN")

>>> arr._cast_pointwise_result([item]).dtype
null[pyarrow]

Issue Description

This goes through pa.array([item], from_pandas=True) so may be an upstream issue.

Expected Behavior

Ideally this should give back a decimal dtype.

Installed Versions

Replace this line with the output of pd.show_versions()