Check the existence of superglobals $_POST['post_ID'] and $_POST['checked']

[waviaei]

We tried to use the plugin, but was request to fix below three superglobal array issues.

Note: the review was done when Public Post Preview was v2.9.1, so the lines 388, 404, and 406 in below report are now 394, 410 and 412 respectively.

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FOUND 3 ERRORS AFFECTING 3 LINES
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 388 | ERROR | Detected usage of a possibly undefined superglobal array index: $_POST['post_ID']. Use isset() or empty() to check the index exists before using it
 404 | ERROR | Detected usage of a possibly undefined superglobal array index: $_POST['checked']. Use isset() or empty() to check the index exists before using it
 406 | ERROR | Detected usage of a possibly undefined superglobal array index: $_POST['checked']. Use isset() or empty() to check the index exists before using it
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I will send the PR, which was worked from v2.9.2.

[waviaei]

@ocean90
Hi, thank you for merging that PR. I don't want to rush you for our convenience, but wondering with your schedule plan for when to release new ver. to .org repo.

Many Thanks!
Toru