A simple Angular service for function composition

composer.factory.js

(function(window, angular) {

    'use strict';

/****
 * Simple composition factory for Angular 1x
*****/
    var composer = angular.module('composerModule', []);
    composer.factory('Composer', Composer);

    function Composer() {
        // basic validation if a custom function is not provided
        var isSafe = function isSafe(val) {
                if(val === undefined || val === null) {
                    return false;
                }
                return true;
            };
        //input validation and check if the function throws an error    
        function fnCheck(fn) {
            return function(value) {
                if( isSafe(value) ) {
                    try{
                        return fn(value);
                    } catch (e){
                        console.log(fn.name + ' error: ' + e);
                        return value;
                    }
                }else {
                    return value;
                }
            };
        }
        //set custom validation
        function setValidator(myCheck) {
            if(typeof myCheck === 'function') {
                isSafe = myCheck;
            }
            return this;
        }
        //pipe the functions to compose
        function pipe() {
            var fns = Array.prototype.slice.call(arguments);
            return fns.reduceRight(function (fn1, fn2) {
                fn1 = fnCheck(fn1);
                fn2 = fnCheck(fn2);
                return function(input) {
                    return fn1(fn2(input));
                };
            });
        }
        return {
            pipe: pipe,
            setValidator: setValidator
        };
    }
}(window, window.angular));