MediaWiki version: 1.36.0-wmf.26
PHP Notice: Undefined offset: 0
A few of this just happened, on testwiki. From sandbox. I assume this is ultimately caused by client error, but the server code should handle those without causing errors or log messages, I think.
I don't know if this is related to T271804: PHP Notice: Undefined index: Alsjdakjsdh but I would assume not, due to the different error message.
URL: /w/api.php (POST, so nor URL parameters)