dealing empty list

CMakeLists.txt

@@ -53,20 +53,22 @@ FIND_PACKAGE(falkolib QUIET)
 find_package(PkgConfig)
 pkg_check_modules(csm QUIET csm )
 link_directories(${csm_LIBRARY_DIRS})
-message(csm_LIBRARY_DIRS: ${csm_LIBRARY_DIRS})
-# keep only the files in a lib folder: by default the "." is in csm_LIBRARY_DIRS, 
-# which is not acceptable for target_link_directories 
-foreach (my_entry IN LISTS csm_LIBRARY_DIRS)
-    message("csm_LIBRARY_DIRS has ${my_entry}")
-endforeach()
-list(FILTER csm_LIBRARY_DIRS INCLUDE REGEX "lib")
-foreach (my_entry IN LISTS csm_LIBRARY_DIRS)
-    message("csm_LIBRARY_DIRS has ${my_entry}")
-endforeach()
-
-
-
-
+if(csm_FOUND)
+  if(NOT csm_LIBRARY_DIRS)
+  message("csm_LIBRARY_DIRS is empty")
+  else()
+    # keep only the files in a lib folder: by default the "." is in csm_LIBRARY_DIRS, 
+    # which is not acceptable for target_link_directories 
+    message(csm_LIBRARY_DIRS:)
+    foreach (my_entry IN LISTS csm_LIBRARY_DIRS)
+        message("csm_LIBRARY_DIRS has ${my_entry}")
+    endforeach()
+    list(FILTER csm_LIBRARY_DIRS INCLUDE REGEX "lib")
+    foreach (my_entry IN LISTS csm_LIBRARY_DIRS)
+        message("csm_LIBRARY_DIRS has ${my_entry}")
+    endforeach()
+  endif()
+endif()
 
 # ============ INCLUDES ============ 
 INCLUDE_DIRECTORIES("include")