tries to provide better guidance on CSRF errors

src/user/routes.ts

@@ -34,7 +34,12 @@ userRouter.use(
     const data: any = { message: err.message, stack: err.stack, status: 500 };
 
     if (req.accepts("json", "html") === "json") {
-      return res.status(500).json({ error: err.message });
+      const isCsrfError = err.message === "invalid csrf token";
+      const message = isCsrfError
+        ? "CSRF token mismatch; try refreshing the page"
+        : err.message;
+
+      return res.status(500).json({ error: message });
     } else {
       return res.status(500).render("user_error", { ...data, flash: null });
     }

src/user/web/views/user_error.ejs

@@ -1,8 +1,11 @@
 <%- include("partials/shared_header", { title: "Error" }) %>
     <div id="error-content" style="color: red; background-color: #eedddd; padding: 1em">
       <p><strong>⚠️ Error <%= status %>:</strong> <%= message %></p>
+      <% if (message.includes('csrf')) { %>
+        <p>ℹ️ Refresh the previous page and then try again. If the problem persists, clear cookies for this site.</p>
+      <% } %>
       <pre><%= stack %></pre>
-      <a href="#" onclick="window.history.back()">Go Back</a>
+      <a href="#" onclick="window.history.back()" style="color:unset">Go Back</a>
     </div>
   </body>
 </html>