Why is get route showing TypeError: Cannot read property 'title' of null and crashing the website? - node.js

Question

i am building an express app with mongodb in nodejs, When i make a get request to the show posts route , then all posts are rendered correctly when i pass them in ejs file but after the show page is displayed it gives an error on the terminal
events.js:291 throw er; // Unhandled 'error' event ^ TypeError: Cannot read property 'title' of null
this is my get route in router/posts.js
router.get("/commerce", (req,res)=>{
if(req.query.search){
var noMatch;
// gives search results on author name, content and title of the post
const regex = new RegExp(escapeRegex(req.query.search), 'gi')
Post.find({$or: [{title:regex} , {content:regex}, {'author.username':regex}], subject: "commerce"}, function(err,allposts){
if(err) console.log(err)
else{
if(allposts.length<1){
noMatch = "No posts matched the search results , please try again"
}
console.log("searched", allposts)
res.render("commerce", {posts: allposts, noMatch: noMatch, message: req.flash('success')});
}
})
} else{
Post.find({subject: "commerce"}, function(err,allposts){
if(err) {
console.log(err);
res.statusCode = 500;
res.end('error');
}
else{
console.log("actually all posts",allposts)
res.render("commerce", {posts: allposts, noMatch: noMatch , message: req.flash('success')});
}
})
}
})
commerce.ejs
<%- include("./partials/header1.ejs") %>
<link rel="stylesheet" href="/stylesheets/commerce.css">
<%- include("./partials/header2.ejs") %>
<div class="top-horiz-bar">
<div class="logo-section-in-bar">
<img class="top-img-logo" src="./finallogopic.png" alt="logo-pic" height="60px" width="60px">
<!-- <img class="top-name-logo" src="./zoomed-brand-name.png" alt="logo-name" height="80px" width="130px"> -->
<h2 class="top-name-logo">Backbanchers</h2>
</div>
<div class="other-icons">
<div class="search-box">
<input id="search-font" class="search-txt" type="text" name="" placeholder="Type to search">
<a class="search-btn" href="#">
<i class="fas fa-search"></i>
</a>
</div>
<div class="person-account">
<a class="account-info" href="#">
<i class="far fa-user-circle fa-2x"></i>
<span>Sign-in/up</span>
</a>
</div>
</div>
</div>
<div class="vertical-nav-bar">
Home<span><i class="fas fa-home"></i></span>
<a class="blog-section-left" href="#">Blogs<span><i class="fas fa-user-graduate"></i></span>
<!-- <ul class="sections-blog">
<a class="option-blog" href="#"><li>Business & Economics</li></a>
<a class="option-blog" href="#"><li>Commerce</li></a>
<a class="option-blog" href="#"><li>Personality Devlopment</li></a>
</ul> -->
</a>
Authors<span><i class="fas fa-pencil-alt"></i></span>
Newsletter<span><i class="fas fa-newspaper"></i></span>
Contact US<span><i class="fas fa-phone-alt"></i></span>
<!-- Services<span><i class="fas fa-question"></i></span> -->
About Us<span><i class="fas fa-users"></i></span>
<!-- Services<span><i class="fas fa-question"></i></span> -->
</div>
<div class="all-engineering-articles">
<div class="side-box">
<div class="one-of-3-heading">
<h2 class="side-box-heading-one">Trending</h2>
<div class="sub-part-section">
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<h2 class="side-box-heading-two">Recommended</h2>
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<div class="three-of-3-heading">
<h2 class="side-box-heading-three">Popular</h2>
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<div class="date-side-box">
<span>15 August 2020</span>
</div>
</div>
</div>
</div>
<% posts.forEach(function(post){ %>
<div class="blog-post">
<div class="blog-post__img">
<img src="https://image.freepik.com/free-photo/cyborg-hand-pressing-keyboard-laptop-3d-rendering_117023-946.jpg" alt="article-pic" class="blog-post__article-img">
</div>
<div class="blog-post__info">
<div class="blog-post__date">
<span><%= post.publishDay%></span>
<span><%= post.publish_date %></span>
</div>
<div class="author-name">
<ul class="author-content">
<li class="name-aut"><%= post.author.username %>></li>
<li class="save-to-later"><i class="fas fa-plus "></i></li>
</ul>
</div>
console.log(<%= post.title %>)
<h1 class="blog-post__title"><%= post.title %></h1>
<p class="blog-post__text"><%= post.content.substring(0,120) %></p>
Read more
<ul class="btns-on-blogcard">
<!-- <li class="btns-blog"><i class="far fa-eye fa-2x "></i></li> -->
<li class="btns-blog"><i class="far fa-hand-peace fa-2x "></i></li>
<li class="btns-blog"><i class="fas fa-share fa-2x "></i></li>
</ul>
</div>
</div>
<% }) %>
<div class="page-end">
</div>
<div class="next-page">
<h2 class="new-page-blogs">-Page 1 of 1- <span class="next-page-btn">Next page</span></h2>
</div>
</div>
<section class="footer" >
<footer id="foo">
<div class="overall-footer">
<div class="first-part">
<h2 class="our-name">Backbenchers</h2>
<img id="logo-of-learners" src="finallogopic.png" alt="our-logo" height="40%" width="14%">
</div>
<div class="bordering-right">
</div>
<div class="second-part">
<h2 class="second-links">Quick Links</h2>
<ul class="ul-class-footer">
<li class="quick-buttons">Home</li>
<li class="quick-buttons">Buisness & Economics</li>
<li class="quick-buttons">Commerce</li>
<li class="quick-buttons">Engineering</li>
<li class="quick-buttons">Personality Devlopment</li>
</ul>
</div>
<div class="third-party">
<div class="name-social-footer">
<li class="quick-buttons-2">Facebook</li>
<li class="quick-buttons-2">Instagram</li>
<li class="quick-buttons-2">LinkedIn</li>
</div>
<style>
a{
text-decoration: none;
color: white;
}
</style>
<div class="media-buttons-footer">
<a class="btns-footer-class-1" href="#"><i id="facebook-1" class="fab fa-facebook-f "></i></a>
<a class="btns-footer-class-2" href="#"><i id="instagram-1" class="fab fa-instagram "></i></a>
<a class="btns-footer-class-3" href="#"><i id="linkedin-1" class="fab fa-linkedin-in "></i></a>
</div>
</div>
<div class="fourth-party">
<h2 class="fourth-links">Social</h2>
<a href="mailto:ritishgupta45#gmail.com">
<span id="envolope-footer" class="fas fa-envelope fa-2x"></span>
<span id="email-footer" class="text">Backbenchers#gmail.com</span>
</a>
<input id="name-id-id" type="email" placeholder="Name">
<input id="email-id-id" type="email" placeholder="Email-id" required>
<input id="leave-msg-id-id" type="text" placeholder="leave a message">
<div class="send-button-footer">
<button id="send-id-id" type="submit">Send</button>
</div>
</div>
<div class="fifth-party">
<h2 class="fifth-links">Connect with Us</h2>
<h2 class="heading-of-news-footer">Newsletter subscription</h2>
<p class="para-of-news-footer">Subscribe to our fortnightly newsletter <br> to gain great knowledge exposure. <br> Also, stand a chance to participate <br> in brainstorming competitions <br> and win exciting prizes.</p>
<div class="suscribe-footer">
<input id="footer-suscribe-btns" type="email" placeholder="enter your email id" required>
<div class="red-btn-suscribe">
<button id="suscribing" type="button">Subscribe</button>
</div>
</div>
</div>
<div class="final-part">
<div class="box-copy">
<div class="btns-margin">
<h2 class="bottom-copy-footer">About Us</h2>
<h2 class="bottom-copy-footer">Privacy Policy</h2></a>
<h2 class="bottom-copy-footer">Terms and conditions</h2>
</div>
<h2 class="final-copywrite">copyright © All Rights Reserved | Backbenchers</h2>
</div>
</div>
</footer>
</section>
<%- include("./partials/footer.ejs") %>
output ss 1 of console.log("actually all posts",allposts)
output ss 2 of console.log("actually all posts",allposts)
in these output ss
i have added console.log("actually all posts",allposts) before res.render() and got the output whrere all posts are printed and at last null is also printed where is that null coming from? , and after this null , error is printed on the console as visible in the scrrenshots above