BUG: unstack/pivot (and other functions) raise TypeError when in debug mode

[djmcnay]

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

# when run in debug mode
data = dict(x=[1, 2, 3], y=[np.nan, 2, 4], z=[5.345, np.nan, 9.0])
df = pd.DataFrame(data).stack()
df = df.unstack()

Issue Description

When de-bugging python 3.10+ (tested on 3.10.4) several functions, including unstack and pivot will raise TypeError 'NoneType'. Problem only exists in debug mode and code works fine when in production or run as a script.

Search the forums seems this may be to do with the way Numpy is interacting with Cython; tested using Numpy 1.22.3 and Cython 0.29.29 and 0.29.30.

Full traceback:

Traceback (most recent call last):
File "C:\Users\XXX.conda\envs\py10\lib\site-packages\numpy\core\getlimits.py", line 649, in init
self.dtype = numeric.dtype(int_type)
TypeError: 'NoneType' object is not callable
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "C:\Program Files\JetBrains\PyCharm 2022.1.1\plugins\python\helpers\pydev\pydevd.py", line 1491, in _exec
pydev_imports.execfile(file, globals, locals) # execute the script
File "C:\Program Files\JetBrains\PyCharm 2022.1.1\plugins\python\helpers\pydev_pydev_imps_pydev_execfile.py", line 18, in execfile
exec(compile(contents+"\n", file, 'exec'), glob, loc)
File "C:/Users/XXX/Documents/GitHub/XXX/playground.py", line 9, in
df = df.unstack()
File "C:\Users\XXX.conda\envs\py10\lib\site-packages\pandas\core\series.py", line 4157, in unstack
return unstack(self, level, fill_value)
File "C:\Users\XXX.conda\envs\py10\lib\site-packages\pandas\core\reshape\reshape.py", line 491, in unstack
unstacker = _Unstacker(
File "C:\Users\XXX.conda\envs\py10\lib\site-packages\pandas\core\reshape\reshape.py", line 133, in init
if num_cells > np.iinfo(np.int32).max:
File "C:\Users\XXX.conda\envs\py10\lib\site-packages\numpy\core\getlimits.py", line 651, in init
self.dtype = numeric.dtype(type(int_type))
TypeError: 'NoneType' object is not callable
python-BaseException

Expected Behavior

Should simply unstack dataframe

Installed Versions

pd.show_versions() just throws
AssertionError: C:\Users\T333208.conda\envs\py10\lib\distutils\core.py

when running python 3.10.4, pandas 1.4.2

[mroeschke]

Thanks for the report. The core issue is being tracked in #41935 so closing.