Assert if Tilemode exceeds maximum index

diff --git a/Source/GmmLib/Texture/GmmTexture.cpp b/Source/GmmLib/Texture/GmmTexture.cpp
index a49b062..28586fb 100644
--- a/Source/GmmLib/Texture/GmmTexture.cpp
+++ b/Source/GmmLib/Texture/GmmTexture.cpp
@@ -479,6 +479,8 @@
             MipHeight = GFX_CEIL_DIV(MipHeight, CompressHeight);
             MipDepth  = GFX_CEIL_DIV(MipDepth, CompressDepth);
         }
+	
+	__GMM_ASSERT(pTexInfo->TileMode < GMM_TILE_MODES);
 
         while((Level < pTexInfo->MaxLod) &&
               (((pTexInfo->Type == RESOURCE_1D) &&