Php8.1 brokes

[chupinmaxime]

Since the servers switch to php8.1, geshi-parse_code() gives the following error:

Warning: Undefined array key "KEYWORDS" in /home/users/mc/metapost-exemples/geshi/geshi.php on line 2040

Fatal error: Uncaught TypeError: array_keys(): Argument #1 ($array) must be of type array, null given in /home/users/mc/metapost-exemples/geshi/geshi.php:2040 Stack trace: #0 /home/users/mc/metapost-exemples/geshi/geshi.php(2040): array_keys() #1 /home/users/mc/metapost-exemples/geshi/geshi.php(2182): GeSHi->build_parse_cache() #2 /home/users/mc/metapost-exemples/fonctions.php(15): GeSHi->parse_code() #3 /home/users/mc/metapost-exemples/exemple.php(21): metapostelement() #4 {main} thrown in /home/users/mc/metapost-exemples/geshi/geshi.php on line 2040