BUG: merge raising for ea int and numpy float

[phofl]

• closes BUG: Merge error when merge col is int64 and Int64 #46178 (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

Ideally I'd like to get this in, but not a blocker

[mroeschke]

mypy.....................................................................Failed
- hook id: mypy
- duration: 105.59s
- exit code: 1

pandas/core/reshape/merge.py:1393: error: Item "dtype[Any]" of "dtype[Any] | ExtensionDtype" has no attribute "construct_array_type"  [union-attr]
pandas/core/reshape/merge.py:1396: error: Item "dtype[Any]" of "dtype[Any] | ExtensionDtype" has no attribute "construct_array_type"  [union-attr]
Found 2 errors in 1 file (checked 1413 source files)

[mroeschke]

Do we know that this will always return an ExtensionDtype? Might be good to first check that it is one

[phofl]

Yeah one more check won't hurt. Updated

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 2.1.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 9939c323e636d580e8ca1690aef40b6822ff02f7

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #54755: BUG: merge raising for ea int and numpy float'

4. Push to a named branch:

git push YOURFORK 2.1.x:auto-backport-of-pr-54755-on-2.1.x

5. Create a PR against branch 2.1.x, I would have named this PR:

"Backport PR #54755 on branch 2.1.x (BUG: merge raising for ea int and numpy float)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[mroeschke]

Thanks @phofl