feat: improve error/exception ui (#3690)

templates/access-denied.html.php

@@ -1,4 +0,0 @@
-
-<h1>
-    Please authenticate in order to access this instance
-</h1>

templates/error.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * This template is for rendering error messages (not exceptions)
+ */
+?>
+
+<?php if (isset($title)): ?>
+    <h1>
+        <?= e($title) ?>
+    </h1>
+<?php endif; ?>
+
+<p>
+    <?= e($message) ?>
+</p>

templates/exception.html.php

@@ -1,3 +1,8 @@
+<?php
+/**
+ * This template is used for rendering exceptions
+ */
+?>
 <div class="error">
 
     <?php if ($e instanceof HttpException): ?>
@@ -12,7 +17,7 @@
         <?php endif; ?>
 
         <?php if ($e->getCode() === 404): ?>
-            <h2>The website was not found</h2>
+            <h2>404 Page Not Found</h2>
             <p>
                 RSS-Bridge tried to fetch a page on a website.
                 But it doesn't exists.
@@ -20,13 +25,21 @@
         <?php endif; ?>
 
         <?php if ($e->getCode() === 429): ?>
-            <h2>Try again later</h2>
+            <h2>429 Try again later</h2>
             <p>
                 RSS-Bridge tried to fetch a website.
                 They told us to try again later.
             </p>
         <?php endif; ?>
 
+        <?php if ($e->getCode() === 503): ?>
+            <h2>503 Service Unavailable</h2>
+            <p>
+                Common causes are a server that is down for maintenance
+                or that is overloaded.
+            </p>
+        <?php endif; ?>
+
     <?php else: ?>
         <?php if ($e->getCode() === 10): ?>
             <h2>The rss feed is completely empty</h2>