Fatal error: Uncaught TypeError: Argument 1 passed to sphereVolume() must be of the type float, null given, called in /home/skilling/webappexamples.skilling.us/web/validation/functions/sphere/sphere.php on line 3 and defined in /home/skilling/webappexamples.skilling.us/web/validation/functions/sphere/sphere.php:24 Stack trace: #0 /home/skilling/webappexamples.skilling.us/web/validation/functions/sphere/sphere.php(3): sphereVolume(NULL) #1 {main} thrown in /home/skilling/webappexamples.skilling.us/web/validation/functions/sphere/sphere.php on line 24