Fix lack of entity argument issue in configuration example (#5084)

Signed-off-by: JesusPoderoso <jesuspoderoso@eprosima.com>

Author: JesusPoderoso

examples/cpp/configuration/CLIParser.hpp

@@ -228,6 +228,12 @@ class CLIParser
     {
         configuration_config config;
 
+        if (argc < 2)
+        {
+            EPROSIMA_LOG_ERROR(CLI_PARSER, "missing entity argument");
+            print_help(EXIT_FAILURE);
+        }
+
         std::string first_argument = argv[1];
 
         if (first_argument == "publisher" )