+ add error pages

web_app/templates/layout.html

@@ -27,7 +27,7 @@
             </button>
             <div class="collapse navbar-collapse" id="navbarToggle">
               <div class="navbar-nav mr-auto">
-                <a class="nav-item nav-link" href="nassi.ole-siepmann.de">Home</a>
+                <a class="nav-item nav-link" href="http://nassi.ole-siepmann.de">Home</a>
                 <a class="nav-item nav-link" href="https://ole-siepmann.de/startseite/datenschutzerklaerung/">Datenschutz</a>
               </div>
               <!-- Navbar Right Side -->