Added middleware that mitigates big error traces being logged for those not using mercure

module/Rest/config/dependencies.config.php

@@ -6,7 +6,9 @@ namespace Shlinkio\Shlink\Rest;
 
 use Laminas\ServiceManager\AbstractFactory\ConfigAbstractFactory;
 use Laminas\ServiceManager\Factory\InvokableFactory;
+use Mezzio\ProblemDetails\ProblemDetailsResponseFactory;
 use Mezzio\Router\Middleware\ImplicitOptionsMiddleware;
+use Psr\Log\LoggerInterface;
 use Shlinkio\Shlink\Common\Mercure\LcobucciJwtProvider;
 use Shlinkio\Shlink\Core\Domain\DomainService;
 use Shlinkio\Shlink\Core\Options;
@@ -49,6 +51,7 @@ return [
             Middleware\ShortUrl\DropDefaultDomainFromRequestMiddleware::class => ConfigAbstractFactory::class,
             Middleware\ShortUrl\DefaultShortCodesLengthMiddleware::class => ConfigAbstractFactory::class,
             Middleware\ShortUrl\OverrideDomainMiddleware::class => ConfigAbstractFactory::class,
+            Middleware\Mercure\NotConfiguredMercureErrorHandler::class => ConfigAbstractFactory::class,
         ],
     ],
 
@@ -90,6 +93,10 @@ return [
             'config.url_shortener.default_short_codes_length',
         ],
         Middleware\ShortUrl\OverrideDomainMiddleware::class => [DomainService::class],
+        Middleware\Mercure\NotConfiguredMercureErrorHandler::class => [
+            ProblemDetailsResponseFactory::class,
+            LoggerInterface::class,
+        ],
     ],
 
 ];

module/Rest/config/routes.config.php

@@ -4,6 +4,8 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Rest;
 
+use Shlinkio\Shlink\Rest\Middleware\Mercure\NotConfiguredMercureErrorHandler;
+
 $contentNegotiationMiddleware = Middleware\ShortUrl\CreateShortUrlContentNegotiationMiddleware::class;
 $dropDomainMiddleware = Middleware\ShortUrl\DropDefaultDomainFromRequestMiddleware::class;
 $overrideDomainMiddleware = Middleware\ShortUrl\OverrideDomainMiddleware::class;
@@ -46,7 +48,7 @@ return [
         Action\Domain\ListDomainsAction::getRouteDef(),
         Action\Domain\DomainRedirectsAction::getRouteDef(),
 
-        Action\MercureInfoAction::getRouteDef(),
+        Action\MercureInfoAction::getRouteDef([NotConfiguredMercureErrorHandler::class]),
     ],
 
 ];

module/Rest/src/Action/MercureInfoAction.php

@@ -10,7 +10,6 @@ use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Shlinkio\Shlink\Common\Mercure\JwtProviderInterface;
 use Shlinkio\Shlink\Rest\Exception\MercureException;
-use Throwable;
 
 use function sprintf;
 
@@ -32,12 +31,7 @@ class MercureInfoAction extends AbstractRestAction
 
         $days = $this->mercureConfig['jwt_days_duration'] ?? 1;
         $expiresAt = Chronos::now()->addDays($days);
-
-        try {
-            $jwt = $this->jwtProvider->buildSubscriptionToken($expiresAt);
-        } catch (Throwable $e) {
-            throw MercureException::mercureNotConfigured($e);
-        }
+        $jwt = $this->jwtProvider->buildSubscriptionToken($expiresAt);
 
         return new JsonResponse([
             'mercureHubUrl' => sprintf('%s/.well-known/mercure', $hubUrl),

module/Rest/src/Exception/MercureException.php

@@ -7,7 +7,6 @@ namespace Shlinkio\Shlink\Rest\Exception;
 use Fig\Http\Message\StatusCodeInterface;
 use Mezzio\ProblemDetails\Exception\CommonProblemDetailsExceptionTrait;
 use Mezzio\ProblemDetails\Exception\ProblemDetailsExceptionInterface;
-use Throwable;
 
 class MercureException extends RuntimeException implements ProblemDetailsExceptionInterface
 {
@@ -16,9 +15,9 @@ class MercureException extends RuntimeException implements ProblemDetailsExcepti
     private const TITLE = 'Mercure integration not configured';
     private const TYPE = 'MERCURE_NOT_CONFIGURED';
 
-    public static function mercureNotConfigured(?Throwable $prev = null): self
+    public static function mercureNotConfigured(): self
     {
-        $e = new self('This Shlink instance is not integrated with a mercure hub.', 1, $prev);
+        $e = new self('This Shlink instance is not integrated with a mercure hub.');
 
         $e->detail = $e->getMessage();
         $e->title = self::TITLE;

module/Rest/src/Middleware/Mercure/NotConfiguredMercureErrorHandler.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Rest\Middleware\Mercure;
+
+use Mezzio\ProblemDetails\ProblemDetailsResponseFactory;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Psr\Log\LoggerInterface;
+use Shlinkio\Shlink\Rest\Exception\MercureException;
+
+class NotConfiguredMercureErrorHandler implements MiddlewareInterface
+{
+    public function __construct(private ProblemDetailsResponseFactory $respFactory, private LoggerInterface $logger)
+    {
+    }
+
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        try {
+            return $handler->handle($request);
+        } catch (MercureException $e) {
+            // Throwing this kind of exception makes a big error trace to be logged, for anyone who has decided to not
+            // use mercure.
+            // It happens every time the shlink-web-client is opened, so this mitigates the problem by just logging a
+            // simple warning, and casting the exception to a response on the fly.
+            $this->logger->warning($e->getMessage());
+            return $this->respFactory->createResponseFromThrowable($request, $e);
+        }
+    }
+}