fix crash on 0 instance

Data/InstanceData.cs

@@ -44,12 +44,15 @@ namespace Kav
 
         public void SetData()
         {
-            VertexBuffer.SetData(
+            if (InstanceCount > 0)
-                InstanceDataArray,
+            {
-                0,
+                VertexBuffer.SetData(
-                InstanceCount,
+                    InstanceDataArray,
-                SetDataOptions.NoOverwrite
+                    0,
-            );
+                    InstanceCount,
+                    SetDataOptions.NoOverwrite
+                );
+            }
         }
 
         public void Clear()