Enhance the web application to handle various error scenarios during the registration process, such as duplicate email addresses or weak passwords, displaying appropriate error messages to users.

<div id="register">
    <div class="container">
	    <form action="/signup" method="post">
		    <h2>Register</h2>
		    <div class="form-group">
			    <label for="email">Email address</label>
		<input type="email" class="form-control" id="email" name="email" placeholder="Enter email">
		    </div>
		    <div class="form-group">
			    <label for="password">Password</label>
			    <input type="password" class="form-control" id="password" name="password" placeholder="Password">
		    </div>
		    <button type="submit" class="btn btn-primary">Register</button>
	    </form>
    </div>
</div>