psalm/docs/running_psalm/issues/UnusedIssueHandlerSuppression.md

UnusedIssueHandlerSuppression

Emitted when an issue type suppression in the configuration file is not being used to suppress an issue.

Enabled by findUnusedIssueHandlerSuppression

<?php
$a = 'Hello, World!';
echo $a;

<?xml version="1.0" encoding="UTF-8"?>
<issueHandlers>
    <PossiblyNullOperand errorLevel="suppress"/>
</issueHandlers>