v20200915 downloadavatar Error

[aksskl]

Upgrading to the latest v20200915 member ids result in an error when downloadavatar=True.

Example Member Id 10292

Processing Member Id: 10292
Page
Member Url: https://www.pixiv.net/ajax/user/10292/profile/all
Member Name : ふーみ
Member Avatar: https://i.pximg.net/user-profile/img/2018/12/05/01/15/26/15093709_d317aa489a6bfbf056842c58fbd5e01c.png
Member Token : tokitoruo
Member Background : no_background
Processing images from 1 to 67 of 67
Traceback (most recent call last):
File "PixivArtistHandler.pyc", line 119, in process_member
File "PixivHelper.pyc", line 393, in create_avabg_filename
IndexError: list index out of range
Error at process_member(): (<class 'IndexError'>, IndexError('list index out of range'), <traceback object at 0x14B66CA8>)
Dumping html to: Error page for member 10292 at page 1.html
Traceback (most recent call last):
File "PixivUtil2.py", line 1146, in main
File "PixivUtil2.py", line 849, in main_loop
File "PixivUtil2.py", line 201, in menu_download_by_member_id
File "PixivArtistHandler.pyc", line 119, in process_member
File "PixivHelper.pyc", line 393, in create_avabg_filename
IndexError: list index out of range

however, another example is member id 11. Even when downloadavatar=True, member id 11 processes normally for some reason.

[Nandaka]

@byjtje related to #789 ?

need to add null check to artistPage.artistBackground.rsplit(".",1)[1]

https://github.com/Nandaka/PixivUtil2/blob/master/PixivHelper.py#L393

[Nandaka]

should be updated in 89f6ec8