Bug in the plugin which rises PHP notice message

When you visit old link or invalid URL you hit 404 page and there is no $post instance. The widget uses is to find sub-pages without checking if there is current page(post) at the moment which adds PHP error in the output if display_errors = On.

Here is my fix.
https://gist.github.com/avladev/e5fa0982cf2be5f6e564
Edits are on line 70 and 76 you can compare with current version of the file.

Bye

https://ww.wp.xz.cn/plugins/pssubpages/