fix 404 on missing logo id

ot_templating/Resources/Private/Partials/Classic/Topbar.html

@@ -4,9 +4,11 @@
 <div id="topbar">
 
     <div class="topbar-logo">
-        <a href="{ot:rootPage.getUri()}" title="{settings.structureName}">
-            <img src="{settings.structureLogoUrl}" alt="{settings.structureName}"/>
-        </a>
+        <f:if condition="{settings.structureLogoId}">
+            <a href="{ot:rootPage.getUri()}" title="{settings.structureName}">
+                <img src="{settings.structureLogoUrl}" alt="{settings.structureName}"/>
+            </a>
+        </f:if>
     </div>
 
     <h1 class="topbar-title">{settings.structureName}</h1>

ot_templating/Resources/Private/Partials/Modern/Menu.html

@@ -20,13 +20,15 @@
 
                         <f:comment><!-- menu logo --></f:comment>
                         <ul class="menu-logo">
-                            <li>
-                                <a href="{ot:rootPage.getUri()}" title="{settings.structureName}">
-                                    <img id="logo_img"
-                                         src="{settings.structureLogoUrl}"
-                                         alt="{settings.structureName}"/>
-                                </a>
-                            </li>
+                            <f:if condition="{settings.structureLogoId}">
+                                <li>
+                                    <a href="{ot:rootPage.getUri()}" title="{settings.structureName}">
+                                        <img id="logo_img"
+                                             src="{settings.structureLogoUrl}"
+                                             alt="{settings.structureName}"/>
+                                    </a>
+                                </li>
+                            </f:if>
                         </ul>
 
                         <f:comment><!-- menu links --></f:comment>