Fix occasional crash when saving MIDI.

I can't figure out why a change has a NULL note; that shouldn't happen, but it
does.  Worse case scenario is some undo loss, so better to print something
informative and soldier on than crash.  Hopefully this will help track down the
real cause with more testing.

1 files changed, 11 insertions, 2 deletions

diff --git a/libs/ardour/midi_model.cc b/libs/ardour/midi_model.cc
index c9c71e7db9..7f8a38454a 100644
--- a/libs/ardour/midi_model.cc
+++ b/libs/ardour/midi_model.cc
@@ -582,8 +582,16 @@ MidiModel::NoteDiffCommand::marshal_change (const NoteChange& change)
 	}
 
 	ostringstream id_str;
-	id_str << change.note->id();
-	xml_change->add_property ("id", id_str.str());
+	if (change.note) {
+		id_str << change.note->id();
+		xml_change->add_property ("id", id_str.str());
+	} else if (change.note_id) {
+		warning << _("Change has no note, using note ID") << endmsg;
+		id_str << change.note_id;
+		xml_change->add_property ("id", id_str.str());
+	} else {
+		error << _("Change has no note or note ID") << endmsg;
+	}
 
 	return *xml_change;
 }
@@ -593,6 +601,7 @@ MidiModel::NoteDiffCommand::unmarshal_change (XMLNode *xml_change)
 {
 	XMLProperty* prop;
 	NoteChange change;
+	change.note_id = 0;
 
 	if ((prop = xml_change->property("property")) != 0) {
 		change.property = (Property) string_2_enum (prop->value(), change.property);