Interpolation nonnumeric error handling
- [x] closes #21662
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Hello @elapuestojoe! Thanks for updating the PR.

 - In the file [`pandas/core/generic.py`](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/core/generic.py), following are the PEP8 issues :

> [Line 6030:29](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/core/generic.py#L6030): [E128](https://duckduckgo.com/?q=pep8%20E128) continuation line under-indented for visual indent
> [Line 6031:29](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/core/generic.py#L6031): [E128](https://duckduckgo.com/?q=pep8%20E128) continuation line under-indented for visual indent
> [Line 6032:29](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/core/generic.py#L6032): [E128](https://duckduckgo.com/?q=pep8%20E128) continuation line under-indented for visual indent

 - In the file [`pandas/tests/generic/test_generic.py`](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/tests/generic/test_generic.py), following are the PEP8 issues :

> [Line 1024:13](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/tests/generic/test_generic.py#L1024): [E128](https://duckduckgo.com/?q=pep8%20E128) continuation line under-indented for visual indent
> [Line 1025:13](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/tests/generic/test_generic.py#L1025): [E128](https://duckduckgo.com/?q=pep8%20E128) continuation line under-indented for visual indent
> [Line 1025:13](https://github.com/pandas-dev/pandas/blob/14e7fd73c4d9650f25f763405b3f536ff99cd0dc/pandas/tests/generic/test_generic.py#L1025): [E129](https://duckduckgo.com/?q=pep8%20E129) visually indented line with same indent as next logical line



##### Comment last updated on July 06, 2018 at 18:16 Hours UTC closing as stale, if you want to continue working, pls ping and we can re-open. you will need to merge master.