Add system exit command for rosparam error

Author: marija-p

src/gps_spoofer.py

@@ -9,6 +9,7 @@
 from geometry_msgs.msg import PoseWithCovarianceStamped, PointStamped
 from std_msgs.msg import Float64
 import tf
+import sys
 
 class GPSSpoofer:
   def __init__(self):
@@ -103,6 +104,7 @@ def callback_odometry(self, data):
         self.point.point.z = self.latest_altitude_message.data
     else:
         rospy.signal_shutdown("Unknown altitude input parameter")
+        sys.exit()
 
     if not self.got_odometry:
         print "GPSSpoofer: initializing timers"