Improve output readibility on automatically shortened recipe

Author: urfeex

src/rtde/rtde_client.cpp

@@ -331,10 +331,11 @@ void RTDEClient::setupOutputs(const uint16_t protocol_version)
       if (!unavailable_variables.empty())
       {
         std::stringstream error_message;
-        error_message << "The following variables are not recognized by the robot: ";
-        std::for_each(unavailable_variables.begin(), unavailable_variables.end(),
-                      [&error_message](const std::string& variable_name) { error_message << variable_name << " "; });
-        error_message << ". Either your output recipe contains errors "
+        error_message << "The following variables are not recognized by the robot:";
+        std::for_each(
+            unavailable_variables.begin(), unavailable_variables.end(),
+            [&error_message](const std::string& variable_name) { error_message << "\n  - '" << variable_name << "'"; });
+        error_message << "\nEither your output recipe contains errors "
                          "or the urcontrol version does not support "
                          "them.";
 
@@ -345,6 +346,7 @@ void RTDEClient::setupOutputs(const uint16_t protocol_version)
 
           // Some variables are not available so retry setting up the communication with a stripped-down output recipe
           resetOutputRecipe(available_variables);
+          return;
         }
         else
         {