ch6 安装完ceres库之后运行自带示例程序正常，但是运行ceres_curve_fitting会出现错误

CMake Error at /usr/local/lib/cmake/Ceres/CeresConfig.cmake:89 (else): Flow control statements are not properly nested. Call Stack (most recent call first): CMakeLists.txt:11 (find_package)

CMake Error at CMakeLists.txt:11 (find_package): find_package Error reading CMake code from "/usr/local/lib/cmake/Ceres/CeresConfig.cmake".