gracefully handle missing .midnam

Fixes bug: Add a .midnam to local preferences.
use it in a session. delete the .midnam,
reload session -> crash

1 files changed, 4 insertions, 3 deletions

diff --git a/libs/ardour/ardour/midi_patch_manager.h b/libs/ardour/ardour/midi_patch_manager.h
index 1b7de6a51d..5ed648b3e7 100644
--- a/libs/ardour/ardour/midi_patch_manager.h
+++ b/libs/ardour/ardour/midi_patch_manager.h
@@ -126,10 +126,11 @@ public:
 
 	std::list<std::string> custom_device_mode_names_by_model(std::string model_name) {
 		if (model_name != "") {
-			return master_device_by_model(model_name)->custom_device_mode_names();
-		} else {
-			return std::list<std::string>();
+			if (master_device_by_model(model_name)) {
+				return master_device_by_model(model_name)->custom_device_mode_names();
+			}
 		}
+		return std::list<std::string>();
 	}
 
 	const MasterDeviceNames::Models& all_models() const { return _all_models; }