linter: unless ain't the same as if

lib/Properties.hs

@@ -363,7 +363,7 @@ checkTileThing removeExits p@(Property name _value) = case name of
         suggestProperty $ Property "jitsiTrigger" "onaction"
 
         -- prevents namespace clashes for jitsi room names
-        if "shared" `isPrefixOf` jitsiRoom then do
+        if not ("shared" `isPrefixOf` jitsiRoom) then do
           assemblyname <- lintConfig configAssemblyTag
           setProperty "jitsiRoom" (assemblyname <> "-" <> jitsiRoom)
           offersJitsi (assemblyname <> "-" <> jitsiRoom)