internal server error 500 with jquery.min.js - php

Question

I am a novice to PHP. Now I am building a simple login-logout system. While trying to log in the system, I got the Internal Server Error with jquery.min.js:4. Here is my code:
Index:
<!-- Login Form -->
<form method="post" id="loginForm">
<div class="modal fade" id="login" tabindex="-1" role="dialog" aria-labelledby="#loginHeading" aria-hidden="true">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
<h4 class="modal-title" id="loginHeading">Login Form</h4>
</div>
<div class="modal-body">
<div id="loginMessage"></div>
<div class="form-group">
<label for="email">Email: </label>
<input type="email" id="email" name="email" class="form-control" required>
</div>
<div class="form-group">
<label for="pass">Password: </label>
<input type="password" id="pass" name="pass" class="form-control" required>
</div>
<div class="row">
<div class="checkbox" >
<div class="pull-left" style="padding-left:20px">
Forget password?
</div>
<label class="pull-right" style="padding-right:20px"><input type="checkbox" name="remember" value=""> Remember me</label>
</div>
</div>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-success pull-left" data-dismiss="modal" data-toggle="modal" data-target="#signUp">Register</button>
<button type="submit" class="btn myBtn">Login</button>
<button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
</div>
</div>
</div>
</div>
Script:
$("#loginForm").submit(function(event) {
event.preventDefault();
var dataPost= $(this).serializeArray();
$.ajax({
url: '4-logIn.php',
type: 'POST',
data: dataPost,
success:function(data){
if (data == "success") {
window.location("mainPageLogin.php");
}
else {
$("#loginMessage").html(data);
}
},
error: function(data){
$('#loginMessage').html('<div class="alert alert-danger"><h5>Error in connection with loginForm</h5></div>');
}
});
});
4-login.php:
``
<?php
session_start();
include '0-connection.php';
$error='';
$email=filter_var($_POST["email"],FILTER_SANITIZE_EMAIL);
$pass=filter_var($_POST["pass"],FILTER_SANITIZE_STRING);
// Query
$email=mysqli_real_escape_string($link,$email);
$pass=mysqli_real_escape_string($link,$pass);
$pass=hash('sha256',$pass);
$sql="SELECT * FROM users WHERE email='$email' AND password='$pass' AND activation='activated'";
$result=mysqli_query($link, $sql);
if (!$result) {
echo "<div class='alert alert-danger'>Error running the query to take user login</div>";
exit;
}
$count= mysqli_num_rows($result);
if ($count !== 1) {
$error="<div class='alert alert-danger'><strong>ERROR:</strong> Wrong username or password. Please try again or Do you want to <a href='#' data-dismiss='modal' data-target='#signUp' data-toggle='modal'>Sign up</a></div>";
echo $error;
}
else {
// Set session
$row=mysqli_fetch_array($result, MYSQLI_ASSOC);
$_SESSION['user_id']=$row['user_id'];
$_SESSION['username']=$row['username'];
$_SESSION['email']=$row['email'];
// Check remember me Box
if (empty($_POST['remember'])) {
echo "success";
}
else {
}
}
?>
This is my error:
demonstration
web response
Please be more specific in your answer because I am very new in programming. Thanks for reading.

Answer 1

Error in 4-logIn.php, if (!result) { must be changed as if (!$result) {