PHP 8.1+: imagefilledpolygon(): Argument #3 ($num_points_or_color) must be greater than or equal to 3

[stevetitus]

In PHP 8.1 the following exception is thrown:

imagefilledpolygon(): Argument #3 ($num_points_or_color) must be greater than or equal to 3

As per the documentation for the function (https://www.php.net/manual/en/function.imagefilledpolygon.php), the third argument specifying number of points is no longer needed. However, when I change all calls to imagefilledpolygon() and omit this argument, I still see the same failure.

The issue logged here (#235) suggests replacing files but this doesn't solve the problem - I believe that it may have targeted PHP 8.0 and that's why it is no longer valid, but I'm not sure.