BUG: Regression in Resample.apply raised error when apply affected only a Series
- [x] closes #36951
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Error was no longer caught as before.

Sorry made a mistake when pushing...
thanks @phofl  @meeseeksdev backport 1.1.x