stop DEBUG_TRACE for MackieControl crashing in some conditions

diff --git a/libs/surfaces/mackie/mackie_control_protocol.cc b/libs/surfaces/mackie/mackie_control_protocol.cc
index 5ee8d31f85f87a73948cde666548129607fbcb34..12bd02f4d3eaaa28b8d84d50be88ad3bccae5264 100644 (file)
--- a/libs/surfaces/mackie/mackie_control_protocol.cc
+++ b/libs/surfaces/mackie/mackie_control_protocol.cc
@@ -2043,7 +2043,8 @@ MackieControlProtocol::select_range (uint32_t pressed)
 
        pull_stripable_range (_down_select_buttons, stripables, pressed);
 
-       DEBUG_TRACE (DEBUG::MackieControl, string_compose ("select range: found %1 stripables, first = %2\n", stripables.size(), stripables.front()->name()));
+       DEBUG_TRACE (DEBUG::MackieControl, string_compose ("select range: found %1 stripables, first = %2\n", stripables.size(),
+                                                          (stripables.empty() ? "null" : stripables.front()->name())));
 
        if (stripables.empty()) {
                return;