Created action to get mercure integration info

module/Rest/src/Exception/MercureException.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+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
+{
+    use CommonProblemDetailsExceptionTrait;
+
+    private const TITLE = 'Mercure integration not configured';
+    private const TYPE = 'MERCURE_NOT_CONFIGURED';
+
+    public static function mercureNotConfigured(?Throwable $prev = null): self
+    {
+        $e = new self('This Shlink instance is not integrated with a mercure hub.', 1, $prev);
+
+        $e->detail = $e->getMessage();
+        $e->title = self::TITLE;
+        $e->type = self::TYPE;
+        $e->status = StatusCodeInterface::STATUS_NOT_IMPLEMENTED;
+
+        return $e;
+    }
+}