InvalidScope

$this is used in a context where it is not available: either outside any class, or inside a static method where no object instance exists.

Example

<?php
class Counter {
    private int $count = 0;

    public static function reset(): void {
        $this->count = 0; // $this is not available in a static method
    }
}

How to fix

Remove the use of $this, change the method to non-static, or use a static property instead.

<?php
class Counter {
    private static int $count = 0;

    public static function reset(): void {
        self::$count = 0;
    }
}