potential OCE in graph processsing (#17921)

Co-authored-by: Petr <[email protected]>

Author: majocha

src/Compiler/Driver/GraphChecking/GraphProcessing.fs

@@ -252,6 +252,7 @@ let processGraphAsync<'Item, 'Result when 'Item: equality and 'Item: comparison>
         let rec queueNode node =
             Async.Start(
                 async {
+                    use! _catch = Async.OnCancel(completionSignal.TrySetCanceled >> ignore)
                     let! res = processNode node |> Async.Catch
 
                     match res with