Actually, I think I just ran into a similar issue with a local test install. When an error occurs during the installation and we want to log it to the error.log file, it's possible that Geeklog tries to call a function that's not ready for use yet (since Geeklog hasn't been installed yet).
Ouch
Try this: Open the file system/lib-plugins.php in a text editor. Go to line 1553 (as reported), which should look like this: