new installer script from #21034 does not work

Steps to reproduce the issue

try to drag and drop install an extension in the extension installer

Expected result

extension installs

Actual result

spinner never stops and errors in the console

installer.min.js:1 POST http://127.0.0.1/cms4/administrator/index.php?option=com_installer&task=install.ajax_upload 500 (Internal Server Error)
(anonymous) @ installer.min.js:1
installer.min.js:1 Uncaught ReferenceError: options is not defined
    at XMLHttpRequest.s.onreadystatechange (installer.min.js:1)
s.onreadystatechange @ installer.min.js:1
XMLHttpRequest.send (async)
(anonymous) @ installer.min.js:1