<p>Severity: Warning</p>
<p>Message: preg_match(): Compilation failed: escape sequence is invalid in character class at offset 20</p>
<p>Filename: store/ARC2_StoreLoadQueryHandler.php</p>
<p>Line Number: 329</p>
Note that the line in question has a comment that it is intended to be deleted.
Noticed this in PHP 7.4, which updated their preg rules. This line:
https://github.com/anvc/scalar/blob/31d2e9c7dec203842785fbec021d3144ae930e9b/system/application/arc/store/ARC2_StoreLoadQueryHandler.php#L329
... errors with:
Note that the line in question has a comment that it is intended to be deleted.