T3D 1.1 Final - Deadlock & crash when using mounted objects - CONFIRMED (THREED-1981)

Build: T3D 1.1 Final (and any pre-final versions of T3D 1.1)

Platform: All/Any

Target: Engine (C++), Mounting objects

Issues:
1. If you have objects in scene mounted and "parent" fails to load, it will crash/deadlock when running outside of VS.
2. If you have prefab where objects mounted and "parent" fails to load, it will always crash.

Steps to Repeat:

//Place following code into .mis file.
      new PointLight() {
         radius = "5";
         isEnabled = "1";
         color = "1 1 1 1";
         brightness = "1";
         castShadows = "0";
         priority = "1";
         animate = "1";
         animationPeriod = "1";
         animationPhase = "1";
         flareScale = "1";
         attenuationRatio = "0 1 1";
         shadowType = "DualParaboloidSinglePass";
         texSize = "512";
         overDarkFactor = "2000 1000 500 100";
         shadowDistance = "400";
         shadowSoftness = "0.15";
         numSplits = "1";
         logWeight = "0.91";
         fadeStartDistance = "0";
         lastSplitTerrainOnly = "0";
         representedInLightmap = "0";
         shadowDarkenColor = "0 0 0 -1";
         includeLightmappedGeometryInShadow = "0";
         position = "0.224487 0.362549 5.43251";
         rotation = "0 0 -1 110.91";
         mountPID = "252d4f17-40bf-11e0-910e-dcc674078c71";
         mountNode = "1";
         mountPos = "0 0 0";
         mountRot = "1 0 0 0";
         canSave = "1";
         canSaveDynamicFields = "1";
         persistentId = "49a09ecd-3dd1-11e0-b058-f824fdb46369";
      };
      new StaticShape() {
         dataBlock = "BadDatablock";
         position = "-0.224487 -0.362427 3.43251";
         rotation = "0 0 -1 5.57327";
         scale = "1 1 1";
         canSave = "1";
         canSaveDynamicFields = "1";
         persistentId = "252d4f17-40bf-11e0-910e-dcc674078c71";
      };

Start debug version of engine and it will crash (deadlock).
If running from VS, it will load fine, except it will spam the console:

GameBase::setDatablockProperty - Could not find data block "BadDatablock"
ShapeBase::onAdd - no datablock on shape 4146:StaticShape ((null))
40: Register object failed for object (null) of class StaticShape.

which is okay (and correct way of handling this).

For the prefab issue, paste the code-part inside prefab and place it in the mission. It will always crash, even when running from debugger.

The prefab-crash happens in:

void SceneObject::resolveMountPID()
{
   if ( mMountPID && !mMount.object )
   {
      SceneObject *obj = dynamic_cast< SceneObject* >( mMountPID->getObject() );
      if ( obj )      
         obj->mountObject( this, mMount.node, mMount.xfm );      
   }
}

as the mMountPID is a valid, but getObject() returns garbage (0xfdfdfdfd) so the dynamic_cast crashes.

Suggested Fix:
None yet.