fix: properly forward return urls where missing

src/Twig/AppExtension.php

@@ -32,6 +32,7 @@ class AppExtension extends AbstractExtension
             new TwigFunction('icon', [AppRuntime::class, 'renderIcon'], ['needs_environment' => true, 'is_safe' => ['html']]),
             new TwigFunction('is_current_route', [AppRuntime::class, 'isCurrentRoute']),
             new TwigFunction('return_url', [AppRuntime::class, 'getEncodedReturnUrl']),
+            new TwigFunction('forwarded_return_url', [AppRuntime::class, 'getForwardedReturnUrl']),
             new TwigFunction('qa_attribute', [AppRuntime::class, 'renderQaAttribute'], ['is_safe' => ['html']]),
             new TwigFunction('has_pickup', [AppRuntime::class, 'hasPickup']),
         ];

src/Twig/AppRuntime.php

@@ -192,6 +192,21 @@ class AppRuntime implements RuntimeExtensionInterface
         return rawurlencode($masterRequest->getRequestUri());
     }
 
+    /**
+     * Passes the return url of the current page on to the next one.
+     *
+     * Used by links that lead deeper into a detail view or trigger an action on it:
+     * they have to keep pointing back at where the user originally came from instead
+     * of at the page they sit on. Null when there is nothing to pass on, so that the
+     * url generator drops the parameter rather than emitting an empty one.
+     */
+    public function getForwardedReturnUrl(): ?string
+    {
+        $returnUrl = $this->requestStack->getMainRequest()?->query->get('r');
+
+        return is_string($returnUrl) && '' !== $returnUrl ? $returnUrl : null;
+    }
+
     public function renderQaAttribute(string $label, ?string $value = null): string
     {
         if ('test' !== $this->environment) {