Fix crash when MackieControlProtocol has gone away.

git-svn-id: svn://localhost/ardour2/branches/3.0@12634 d708f5d6-7413-0410-9779-e7cbd77b26cf

diff --git a/libs/surfaces/mackie/fader.cc b/libs/surfaces/mackie/fader.cc
index 4a6c81f491315a05006692a88abe7bd821f78f33..4b9da7226a335ef62bbf64f8953a774cd639a7f7 100644 (file)
--- a/libs/surfaces/mackie/fader.cc
+++ b/libs/surfaces/mackie/fader.cc
@@ -47,7 +47,8 @@ Fader::set_position (float normalized)
 MidiByteArray
 Fader::update_message ()
 {
-       if (MackieControlProtocol::instance()->flip_mode() == MackieControlProtocol::Zero) {
+       MackieControlProtocol* mcp = MackieControlProtocol::instance ();
+       if (mcp && mcp->flip_mode() == MackieControlProtocol::Zero) {
                /* do not send messages to move the faders when in this mode */
                return MidiByteArray();
        }