CMakeIOSInstallCombined: add some sanity checks

Modules/CMakeIOSInstallCombined.cmake

@@ -254,6 +254,13 @@ function(ios_install_combined target destination)
     )
   endif()
   set(_lipo_path ${output})
+  list(LENGTH _lipo_path len)
+  if(NOT len EQUAL 1)
+    message(FATAL_ERROR "Unexpected xcrun output: ${_lipo_path}")
+  endif()
+  if(NOT EXISTS "${_lipo_path}")
+    message(FATAL_ERROR "File not found: ${_lipo_path}")
+  endif()
 
   set(CURRENT_CONFIG "${CMAKE_INSTALL_CONFIG_NAME}")
   set(CURRENT_TARGET "${target}")