d3d10/effect: Handle NULL blend state assignments.

dlls/d3d10/effect.c

@@ -1699,6 +1699,10 @@ static BOOL read_value_list(const char *data, size_t data_size, DWORD offset,
                 *(void **)out_data = &null_depth_stencil_variable;
                 break;
 
+            case D3D10_SVT_BLEND:
+                *(void **)out_data = &null_blend_variable;
+                break;
+
             default:
                 FIXME("Unhandled out_type %#x.\n", out_type);
                 return FALSE;