internal/lockedfile: keep objects alive while stopping cleanups

Fixes https://go.dev/issues/74780.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/lockedfile/lockedfile.go

@@ -94,6 +94,11 @@ func (f *File) Close() error {
 
 	err := closeFile(f.osFile.File)
 	f.cleanup.Stop()
+	// f may be dead at the moment after we access f.cleanup,
+	// so the cleanup can fire before Stop completes. Keep f
+	// alive while we call Stop. See the documentation for
+	// runtime.Cleanup.Stop.
+	runtime.KeepAlive(f)
 	return err
 }