Make sure rack mode has forced-stereo option on

source/backend/engine/CarlaEngine.cpp

@@ -1209,6 +1209,12 @@ void CarlaEngine::setOption(const EngineOption option, const int value, const ch
     if (isRunning() && (option == ENGINE_OPTION_PROCESS_MODE || option == ENGINE_OPTION_AUDIO_NUM_PERIODS || option == ENGINE_OPTION_AUDIO_DEVICE))
         return carla_stderr("CarlaEngine::setOption(%i:%s, %i, \"%s\") - Cannot set this option while engine is running!", option, EngineOption2Str(option), value, valueStr);
 
+    if (option == ENGINE_OPTION_FORCE_STEREO && pData->options.processMode == ENGINE_PROCESS_MODE_CONTINUOUS_RACK)
+    {
+        // do not un-force stereo for rack mode
+        CARLA_SAFE_ASSERT_RETURN(value == 1,);
+    }
+
     switch (option)
     {
     case ENGINE_OPTION_DEBUG:

source/backend/engine/CarlaEngineInternal.cpp

@@ -160,6 +160,7 @@ bool CarlaEngine::ProtectedData::init(const char* const clientName)
     {
     case ENGINE_PROCESS_MODE_CONTINUOUS_RACK:
         maxPluginNumber = MAX_RACK_PLUGINS;
+        options.forceStereo = true; // just in case
         break;
     case ENGINE_PROCESS_MODE_PATCHBAY:
         maxPluginNumber = MAX_PATCHBAY_PLUGINS;