how to add if condition for avatar image
<?php
$authorpic = get_the_author_meta('author_pic');
if ($authorpic)
echo $authorpic;
else
echo get_avatar( get_the_author_email(), '80' );
?>
or
<?php
$avatar_url = get_avatar_url( $ID, array( 'size'=>200, 'default'=>'404' ) );
if( getimagesize( $avatar_url ) > 1 )
{
echo '<img src="'. $avatar_url .'" alt="" class="avatar avatar-200">';
} ?>