Multisite network admin throws exception on non-existing array key

When the plugin is active on (at least) the main site of a multiste nework, the network admin panel throws an exception:
Undefined array key "gamipress" in the function gamipress_admin_menu_fix in gamipress/includes/admin.php

The menu item re-ordering is done whether or not the gamipress key exists on the $submenu array. Moving the affecting lines (128-135) inside the conditonal above them fixes it. Also see this gist revision I’ve made: https://gist.github.com/unlocdavid/f9d9f3bcaee8b5f3f9b7d0bf978a4ae3/revisions#diff-bc2bbf2801e44b5801dbd98d39b34f63ce5c7e874d8d1e5a89967b636432578c