<?php if (get_the_author_meta('description')) {  ?>
    <?php
    $author_ID = get_the_author_meta('ID');
    $username = get_the_author_meta('display_name', $author_ID); ?>
    <div class="mm-author-box">
        <figure class="mm-author-box-avatar">
            <?php echo get_avatar($author_ID, 70); ?>
        </figure>
        <?php if ($author_ID === 4) { ?>
            <div class="mm-author-name">
                <a href="<?php echo "http://google.com" ?>"> <?php echo $username; ?> </a>
            </div>
            <div class="mm-author-bio">
                <?php echo get_the_author_meta('description'); ?>
            </div>
    </div>
    <?php } ?>
    <?php else { ?>
        <?php if ($author_ID === 9) { ?>
            <div class="mm-author-name">
                <a href="<?php echo "http://yahoo.com" ?>"> <?php echo $username; ?> </a>
            </div>
            <div class="mm-author-bio">
                <?php echo get_the_author_meta('description'); ?>
            </div>
        </div>
        <?php } ?>
<?php } ?>
It is a code to display author name and hyper link it.
From the first if statement if author has a description then go inside
Second if statement: if authors ID is 4 then execute the code below if not then
Else, there is one extra div inside the else statement which is for <div class="mm-author-box"> which is outside the if statement. 
The problem is that when I put this code it breaks the page.. Only the header of the website loads and the content below it doesn't because i have placed this code in the php file which is a template for the page content.
I think there is some syntax problem coz I used the code without else statement and it worked.
 
     
     
    