Не могу найти ошибку в слайдере

var formSlider = document.querySelector('#form-slider'), 
    divSlideArray = formSlider.querySelectorAll('.slide'); 
 
var divSliderArrows = document.querySelector('#slider-arrows'), 
    divArrowLeft = divSliderArrows.querySelector('.arrow-left'), 
    divArrowRight = divSliderArrows.querySelector('.arrow-right'); 
 
var currentSlide = 0; 
 
divArrowLeft.addEventListener('click', function () { 
    if (currentSlide > 0) { 
        divArrowRight.style.setProperty('display', 'block', ''); 
 
        divSlideArray[currentSlide].style.setProperty('display', 'none', ''); 
        divSlideArray[--currentSlide].style.setProperty('display', 'block', ''); 
 
        if (currentSlide == 0) 
            divArrowLeft.style.setProperty('display', 'none', ''); 
    } 
}); 
 
divArrowRight.addEventListener('click', function () { 
    if (currentSlide < divSlideArray.length - 1) { 
        divArrowLeft.style.setProperty('display', 'block', ''); 
 
        divSlideArray[currentSlide].style.setProperty('display', 'none', ''); 
        divSlideArray[++currentSlide].style.setProperty('display', 'block', ''); 
 
        if (currentSlide == divSlideArray.length - 1) 
            divArrowRight.style.setProperty('display', 'none', ''); 
    } 
 
});

input[type='radio'], 
label { 
    cursor: pointer; 
    height: 22px; 
    width: 22px; 
    background: #494949; 
} 
 
.wrap-slider { 
    position: relative; 
} 
 
#form-slider { 
    width: auto; 
} 
 
#form-slider .slide { 
    margin: 15% auto; 
    overflow: hidden; 
} 
 
#form-slider .slide:first-child ~ .slide { 
    display: none; 
} 
 
#slider-arrows [class^="arrow"] { 
     
    user-select: none; 
    cursor: pointer; 
    background: #4991e3; 
    color: #fff; 
    font-size: 14px; 
    border-radius: 30px; 
    padding: 15px 60px; 
    margin: 0 40px 40px; 
    font-weight: 700; 
} 
 
#slider-arrows .arrow-left { 
    display: none; 
    left: 0; 
} 
 
#slider-arrows .arrow-right { 
    float: right; 
} 
 
.slide { 
    color: #fff; 
    background: #494949; 
    box-shadow: 0 0 10px rgba(0,0,0,0.5); 
} 
 
.heading { 
    font-size: 28px; 
    padding: 4% 6%; 
    display: inline-flex; 
} 
 
.heading i { 
    padding-right: 10px; 
    color: #4991e3; 
    font-size: 22px; 
} 
 
.num { 
    font-size: 14px; 
    padding-left: 100px; 
} 
 
.first { 
    border-bottom: 5px solid #C9C9C9; 
} 
 
.radio { 
    padding: 20px; 
    font-size: 22px; 
    padding: 4% 6%; 
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
<section> 
	<div class="container"> 
	    <div class="wrap-slider"> 
	        <form id="form-slider" action="" method="post"> 
	            <div class="slide"> 
	            	<div class="heading first"> 
	            		<i class="fa fa-file-text-o" aria-hidden="true"></i> 
 
	            		<p>Пройди тест за 2 минуты, и узнай как удвоить поток клиентов в свой бизенс! Чек-лист по маркетингу стоимостью 20.000 р в подарок</p> 
 
	            		<div class="num">1/6</div> 
	            	</div> 
 
	            	<div class="radio"> 
		                <p>Ваш бизнес продвигается с помощью сети интернет ?</p> 
		                <p> 
		                	<input type="radio" name="radio1" id="answer1" value="answer1"> 
		                	<label for="answer1">&nbsp&nbspДа</label> 
		                </p> 
		                <p> 
		                	<input type="radio" name="radio1" id="answer2" value="answer2"> 
		                	<label for="answer2">&nbsp&nbspНет</label> 
		                </p> 
		            </div> 
					 
					<div id="slider-arrows"> 
	            		<!--<div class="arrow-left">Назад</div>--> 
	            		<div class="arrow-right">Вперед</div> 
	        		</div> 
	            </div> 
 
	            <div class="slide"> 
	                <p>Вопрос 2</p> 
	                <p>Ответ <input type="radio" name="radio2" value="answer1"></p> 
	                <p>Ответ <input type="radio" name="radio2" value="answer2"></p> 
	                <p>Ответ <input type="radio" name="radio2" value="answer3"></p> 
 
					<div id="slider-arrows"> 
	            		<div class="arrow-left">Назад</div> 
	            		<div class="arrow-right">Вперед</div> 
	        		</div> 
	            </div> 
 
	            <div class="slide"> 
	                <p>Вопрос 3</p> 
	                <p>Ответ <input type="radio" name="radio3" value="answer1"></p> 
	                <p>Ответ <input type="radio" name="radio3" value="answer2"></p> 
	                <p>Ответ <input type="radio" name="radio3" value="answer3"></p> 
	            </div> 
 
	            <div class="slide"> 
	                <p>Конец</p> 
	                <p><input type="text" name="name" placeholder="Введите Ваше имя"></p> 
	                <p><input type="text" name="phone" id="phone" placeholder="Введите Ваш номер"></p> 
	                <p><input type="email" name="email" placeholder="Введите Ваше мыло"></p> 
	                <p><input type="submit" name="save"></p> 
	            </div> 
	        </form> 
	    </div> 
	</div> 
</section>