You must provide a value expression on the right-hand side of the '-' operator.
At C:\scripts\Steam-GetOnTop-master\Publish-SteamAppManifests.ps1:419 char:
79
+ $libraryIDs += $xmlLibrary.gamesList.games.game.appID | Where
-Object {$_ - <<<< notin $libraryIDs}
+ CategoryInfo : ParserError: (:) [], ParseException
+ FullyQualifiedErrorId : ExpectedValueExpression
Can't run
.\Publish-SteamAppManifests.ps1
Error: