Fix very rare crash on startup

src/sound/AudioInstrumentMixer.cpp

@@ -14,7 +14,7 @@
 */
 
 #define RG_MODULE_STRING "[AudioInstrumentMixer]"
-#define RG_NO_DEBUG_PRINT 1
+#define RG_NO_DEBUG_PRINT
 
 #include "AudioInstrumentMixer.h"
 
@@ -105,7 +105,17 @@ AudioInstrumentMixer::AudioInstrumentMixer(SoundDriver *driver,
         pluginVector.resize(Instrument::PLUGIN_COUNT, nullptr);
     }
 
-#ifndef NDEBUG
+    // Make room for the busses here.
+    const int bussCount = AudioBussMixer::getMaxBussCount();
+
+    // Submaster busses start at 1.  Buss 0 is the master out and it cannot
+    // have effects plugins.
+    for (int i = 1; i < bussCount + 1; ++i) {
+        PluginList &pluginVector = m_plugins[i];
+        pluginVector.resize(Instrument::PLUGIN_COUNT, nullptr);
+    }
+
+#if 0
     RG_DEBUG << "ctor: m_plugins size:" << m_plugins.size();
     for (const auto &pair : m_plugins) {
         RG_DEBUG << "      [" << pair.first << "].size():" << pair.second.size();
@@ -133,7 +143,7 @@ AudioInstrumentMixer::getInstance()
 
 AudioInstrumentMixer::~AudioInstrumentMixer()
 {
-#ifndef NDEBUG
+#if 0
     RG_DEBUG << "dtor: m_plugins size:" << m_plugins.size();
     for (const auto &pair : m_plugins) {
         RG_DEBUG << "      [" << pair.first << "].size():" << pair.second.size();
@@ -743,23 +753,6 @@ AudioInstrumentMixer::generateBuffers()
 
     }
 
-    // Make room for up to 16 busses here, to avoid reshuffling later
-    int busses = 16;
-    if (m_bussMixer)
-        busses = std::max(busses, m_bussMixer->getBussCount());
-    for (int i = 0; i < busses; ++i) {
-        PluginList &list = m_plugins[i + 1];
-        while ((unsigned int)list.size() < Instrument::PLUGIN_COUNT) {
-            // ??? NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-            //     Well, here's the problem.  These were supposed
-            //     to be set up in advance so that we would never
-            //     do this and therefore keep things thread safe.
-            //     This throws that right out the window and explains
-            //     the rare crashes I am seeing.
-            list.push_back(nullptr);
-        }
-    }
-
 }
 
 void

src/sound/AudioProcess.h

@@ -101,6 +101,14 @@ class AudioBussMixer : public AudioThread
      */
     void emptyBuffers();
 
+    /**
+     * Not sure this is the best place, but we really need this so that
+     * we can make the system easily expandable.
+     *
+     * I think we can only actually have 8, so 16 should be ok.
+     * Audio Mixer > Settings > Number of Submasters.
+     */
+    static int getMaxBussCount()  { return 16; }
     int getBussCount() const {
         return m_bussCount;
     }