decoder: do not try to fetch attachments if there is no input

src/input/decoder.c

@@ -659,7 +659,11 @@ static int DecoderGetInputAttachments( decoder_t *p_dec,
                                        input_attachment_t ***ppp_attachment,
                                        int *pi_attachment )
 {
-    return input_Control( p_dec->p_owner->p_input, INPUT_GET_ATTACHMENTS,
+    input_thread_t *p_input = p_dec->p_owner->p_input;
+
+    if( unlikely(p_input == NULL) )
+        return VLC_ENOOBJ;
+    return input_Control( p_input, INPUT_GET_ATTACHMENTS,
                           ppp_attachment, pi_attachment );
 }
 static mtime_t DecoderGetDisplayDate( decoder_t *p_dec, mtime_t i_ts )