Script might well override a static map, but can't risk it not doing it, and preview completely failing. Better to just not try it for static maps. Some script cfg might help. Could also avoid unnnecessary preview regenerations even if the script was doing nothing at all.
# Find Sparkle.framework
#
# Once done this will define
# SPARKLE_FOUND - system has Sparkle
# SPARKLE_INCLUDE_DIR - the Sparkle include directory
# SPARKLE_LIBRARY - The library needed to use Sparkle
# Copyright (c) 2009, Vittorio Giovara <vittorio.giovara@gmail.com>
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
include(FindPackageHandleStandardArgs)
find_path(SPARKLE_INCLUDE_DIR Sparkle.h)
find_library(SPARKLE_LIBRARY NAMES Sparkle)
find_package_handle_standard_args(Sparkle DEFAULT_MSG SPARKLE_INCLUDE_DIR SPARKLE_LIBRARY)
mark_as_advanced(SPARKLE_INCLUDE_DIR SPARKLE_LIBRARY)