do not run calibration if no feature finders (#167)

due to misconfiguration (for instance, camera_info topic
is wrong) the finders may not initialize but the robot
will move through all the poses, say it captured
all of them, and then have no observations in the
output bagfile

robot_calibration/include/robot_calibration/finders/loader.hpp

@@ -90,6 +90,17 @@ class FeatureFinderLoader
       {
         features[name] = finder;
       }
+      else
+      {
+        RCLCPP_ERROR(logger, "Feature finder %s failed to initialize", name.c_str());
+      }
+    }
+
+    // Make sure at least one finder loaded correctly
+    if (features.empty())
+    {
+      RCLCPP_FATAL(logger, "No feature finders loaded");
+      return false;
     }
 
     return true;

robot_calibration/src/nodes/calibrate.cpp

@@ -87,7 +87,11 @@ int main(int argc, char** argv)
   {
     // No name provided for a calibration bag file, must do capture
     robot_calibration::CaptureManager capture_manager;
-    capture_manager.init(node);
+    if (!capture_manager.init(node))
+    {
+      // Error will be printed in function
+      return -1;
+    }
 
     // Save URDF for calibration/export step
     description_msg.data = capture_manager.getUrdf();