SL-6306 Viewer freeze and crash on octree

indra/llmath/lloctree.h

@@ -401,7 +401,7 @@ class LLOctreeNode : public LLTreeNode<T>
 				child->insert(data);
 			}
 		}
-		else 
+		else if (parent)
 		{
 			//it's not in here, give it to the root
 			OCT_ERRS << "Octree insertion failed, starting over from root!" << LL_ENDL;
@@ -416,6 +416,13 @@ class LLOctreeNode : public LLTreeNode<T>
 
 			node->insert(data);
 		}
+		else
+		{
+			// It's not in here, and we are root.
+			// LLOctreeRoot::insert() should have expanded
+			// root by now, something is wrong
+			OCT_ERRS << "Octree insertion failed! Root expansion failed." << LL_ENDL;
+		}
 
 		return false;
 	}
@@ -763,10 +770,15 @@ class LLOctreeRoot : public LLOctreeNode<T>
 			{
 				LLOctreeNode<T>::insert(data);
 			}
-			else
+			else if (node->isInside(data->getPositionGroup()))
 			{
 				node->insert(data);
 			}
+			else
+			{
+				// calling node->insert(data) will return us to root
+				OCT_ERRS << "Failed to insert data at child node" << LL_ENDL;
+			}
 		}
 		else if (this->getChildCount() == 0)
 		{