helper/seccomp: panic on invalid closeWrite use

Returning an error here puts exporter in an invalid state. The caller should guard against this condition instead.

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

helper/seccomp/export.go

@@ -40,7 +40,7 @@ func (e *exporter) closeWrite() error {
 		return *e.closeErr.Load()
 	}
 	if e.w == nil {
-		return fs.ErrInvalid
+		panic("closeWrite called on invalid exporter")
 	}
 	err := e.w.Close()
 	e.closeErr.Store(&err)