Use double quotes in errors/index.html

errors/index.html

@@ -23,7 +23,7 @@
     <body bgcolor="black" text="white">
         <center>
             <h1>{{ $full_text }}</h1>
-            <img src='{{ $img_url }}' alt="cat" />
+            <img src="{{ $img_url }}" alt="cat" />
         </center>
     </body>
 </html>