Convert form select box from .pug to .ejs - node.js

Question

I'm trying to convert the below from pug to ejs. It's a select box of authors (from an associated collection) in a form to add a book to the db. It throws error "Cannot read property '_id' of undefined" pointing to the first option element when I add a new book (but I can update an existing book for some reason). And in the pug version it doesn't throw this error. Is my conversion right?
select#author.form-control(type='select', placeholder='Select author' name='author' required='true' )
- authors.sort(function(a, b) {let textA = a.family_name.toUpperCase(); let textB = b.family_name.toUpperCase(); return (textA < textB) ? -1 : (textA > textB) ? 1 : 0;});
for author in authors
if book
option(value=author._id selected=(author._id.toString()==book.author._id.toString() ? 'selected' : false) ) #{author.name}
else
option(value=author._id) #{author.name}
My conversion:
<select class="form-control" id="author" type="select" placeholder="Select author" name="author" required="true">
<% authors.sort(function(a, b) {let textA = a.family_name.toUpperCase(); let textB = b.family_name.toUpperCase(); return (textA < textB) ? -1 : (textA > textB) ? 1 : 0;}); %>
<% authors.forEach(function(author) { %>
<% if(typeof book !== 'undefined') { %>
<option value="<%= author._id %>" selected=<%= (author._id.toString() == book.author._id.toString()) ? 'selected' : 'false' %>><%= author.name %></option>
<% } else { %>
<option value="<% author._id %>"><%= author.name %></option>
<% } %>
<% }) %>
</select>

Answer 1

The conversion is right. Just a little mistake here <%= instead of <%
<option value="<%= author._id %>"><%= author.name %></option>
For any reason book.author is not present. Pug is catching undefined variables and continues rendering while ejs doesn't. So there is something wrong in your data.
Modify this line to prevent the error <% if(typeof book !== 'undefined' && 'author' in book) { %>
<select class="form-control" id="author" type="select" placeholder="Select author" name="author" required="true">
<% authors.sort(function(a, b) {let textA = a.family_name.toUpperCase(); let textB = b.family_name.toUpperCase(); return (textA < textB) ? -1 : (textA > textB) ? 1 : 0;}); %>
<% authors.forEach(function(author) { %>
<% if(typeof book !== 'undefined' && 'author' in book) { %>
<option value="<%= author._id %>" selected=<%= (author._id.toString() == book.author._id.toString()) ? 'selected' : 'false' %>><%= author.name %></option>
<% } else { %>
<option value="<%= author._id %>"><%= author.name %></option>
<% } %>
<% }) %>
</select>