if values present, fill it in sign up form

templates/user/create_user.twig

@@ -3,13 +3,13 @@
 <form class="ui form" action="/users" method="post">
 <h4 class="ui dividing header">Sign Up</h4>
     <div class="field">
-        <input type="text" name="firstname" id="firstname" placeholder="Firstname" required>
+        <input type="text" name="firstname" id="firstname" placeholder="Firstname" value="{{firstname}}" required>
     </div>
     <div class="field">
-        <input type="text" name="lastname" id="lastname" placeholder="Lastname" required>
+        <input type="text" name="lastname" id="lastname" placeholder="Lastname" value="{{lastname}}" required>
     </div>
     <div class="field">
-        <input type="text" name="username" id="username" placeholder="Username" required>
+        <input type="text" name="username" id="username" placeholder="Username" value="{{username}}" required>
         <div class="ui error message">
             <div class="header">Action Forbidden</div>
             <p>Username already used.</p>
@@ -22,7 +22,7 @@
         <input type="password" name="confirmpassword" id="confirmpassword" placeholder="Confirm your password" required>
     </div>
     <div class="field">
-        <input type="email" name="mail" id="mail" placeholder="Email" required>
+        <input type="email" name="mail" id="mail" placeholder="Email" value="{{mail}}" required>
         <div class="ui warning message">
             <div class="header">Could you check something!</div>
             <ul class="list">