BUG: Cannot slice index using boolean type series

[ChiQiao]

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Reproducible Example

import pandas as pd
s = pd.Series([True, False, pd.NA], dtype="boolean")
s.index[s]

Issue Description

Get the following error: ValueError: cannot convert to 'bool'-dtype NumPy array with missing values. Specify an appropriate 'na_value' for this dtype.

Expected Behavior

Returns pd.Int64Index([0])

Installed Versions

INSTALLED VERSIONS

commit : bb1f651
python : 3.9.10.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19043
machine : AMD64
processor : Intel64 Family 6 Model 142 Stepping 10, GenuineIntel
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : English_United States.1252

pandas : 1.4.0
numpy : 1.22.1
pytz : 2021.3
dateutil : 2.8.2
pip : 22.0.2
setuptools : 59.8.0
Cython : None
pytest : 6.2.5
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : 3.0.2
lxml.etree : 4.7.1
html5lib : None
pymysql : 1.0.2
psycopg2 : None
jinja2 : 3.0.3
IPython : 7.30.1
pandas_datareader: None
bs4 : 4.10.0
bottleneck : None
fastparquet : 0.8.0
fsspec : 2021.11.1
gcsfs : None
matplotlib : 3.5.1
numba : None
numexpr : 2.7.3
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : 3.0.0
pyreadstat : None
pyxlsb : None
s3fs : 0.4.2
scipy : 1.7.3
sqlalchemy : 1.4.31
tables : 3.7.0
tabulate : 0.8.9
xarray : 0.21.1
xlrd : 2.0.1
xlwt : None
zstandard : None