Function assertArg

tools/ngui/static/js/lib/angular.js:1037–1042

* throw error if the argument is falsy.

(arg, name, reason)

 * throw error if the argument is falsy.
 */
function assertArg(arg, name, reason) {
  if (!arg) {
    throw new Error("Argument '" + (name || '?') + "' is " + (reason || "required"));
  }
  return arg;
}

function assertArgFn(arg, name, acceptArrayAnnotation) {
  if (acceptArrayAnnotation && isArray(arg)) {