check result of get_parameter(plugin_lib_names)

Signed-off-by: Davide Faconti <[email protected]>

nav2_bt_navigator/src/bt_navigator.cpp

@@ -75,11 +75,17 @@ BtNavigator::on_configure(const rclcpp_lifecycle::State & /*state*/)
   // Libraries to pull plugins (BT Nodes) from
   std::vector<std::string> plugin_lib_names;
   boost::split(plugin_lib_names, nav2::details::BT_BUILTIN_PLUGINS, boost::is_any_of(";"));
-  auto user_defined_plugins = get_parameter("plugin_lib_names").as_string_array();
-  // append user_defined_plugins to plugin_lib_names
-  plugin_lib_names.insert(
-    plugin_lib_names.end(), user_defined_plugins.begin(),
-    user_defined_plugins.end());
+
+  rclcpp::Parameter plugins_param;
+  if(get_parameter("plugin_lib_names", plugins_param) && 
+     plugins_param.get_type() == rclcpp::ParameterType::PARAMETER_STRING_ARRAY)
+  {
+    auto user_defined_plugins = plugins_param.as_string_array();
+    // append user_defined_plugins to plugin_lib_names
+    plugin_lib_names.insert(
+      plugin_lib_names.end(), user_defined_plugins.begin(),
+      user_defined_plugins.end());
+  }
 
   nav2_core::FeedbackUtils feedback_utils;
   feedback_utils.tf = tf_;