Function assertDefined

lib/web/polyfill.js:345–348

(it)

  if(!condition)throw TypeError(msg2 ? msg1 + msg2 : msg1);
}
function assertDefined(it){
  if(it == undefined)throw TypeError('Function called on null or undefined');
  return it;
}
function assertFunction(it){
  assert(isFunction(it), it, ' is not a function!');
  return it;