Fix coverity defects

apps/openmw/mwphysics/physicssystem.cpp

@@ -709,7 +709,7 @@ namespace MWPhysics
     bool PhysicsSystem::isOnSolidGround (const MWWorld::Ptr& actor) const
     {
         const Actor* physactor = getActor(actor);
-        if (!physactor->getOnGround())
+        if (!physactor || !physactor->getOnGround())
             return false;
 
         CollisionMap::const_iterator found = mStandingCollisions.find(actor);

apps/openmw/mwsound/openal_output.cpp

@@ -363,9 +363,9 @@ OpenAL_SoundStream::OpenAL_SoundStream(ALuint src, DecoderPtr decoder)
 
         switch(type)
         {
-            case SampleType_UInt8: mSilence = 0x80;
-            case SampleType_Int16: mSilence = 0x00;
-            case SampleType_Float32: mSilence = 0x00;
+            case SampleType_UInt8: mSilence = 0x80; break;
+            case SampleType_Int16: mSilence = 0x00; break;
+            case SampleType_Float32: mSilence = 0x00; break;
         }
 
         mFrameSize = framesToBytes(1, chans, type);

apps/openmw/mwsound/soundmanagerimp.cpp

@@ -48,9 +48,6 @@ namespace MWSound
         , mListenerUp(0,0,1)
         , mPausedSoundTypes(0)
     {
-        if(!useSound)
-            return;
-
         mMasterVolume = Settings::Manager::getFloat("master volume", "Sound");
         mMasterVolume = std::min(std::max(mMasterVolume, 0.0f), 1.0f);
         mSFXVolume = Settings::Manager::getFloat("sfx volume", "Sound");
@@ -67,6 +64,9 @@ namespace MWSound
         mBufferCacheMax *= 1024*1024;
         mBufferCacheMin = std::min(mBufferCacheMin*1024*1024, mBufferCacheMax);
 
+        if(!useSound)
+            return;
+
         std::string hrtfname = Settings::Manager::getString("hrtf", "Sound");
         int hrtfstate = Settings::Manager::getInt("hrtf enable", "Sound");