Converted NonUniqueSlugException into a problem details exception

module/Core/src/Exception/NonUniqueSlugException.php

@@ -4,10 +4,19 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Core\Exception;
 
+use Fig\Http\Message\StatusCodeInterface;
+use Zend\ProblemDetails\Exception\CommonProblemDetailsExceptionTrait;
+use Zend\ProblemDetails\Exception\ProblemDetailsExceptionInterface;
+
 use function sprintf;
 
-class NonUniqueSlugException extends InvalidArgumentException
+class NonUniqueSlugException extends InvalidArgumentException implements ProblemDetailsExceptionInterface
 {
+    use CommonProblemDetailsExceptionTrait;
+
+    private const TITLE = 'Invalid custom slug';
+    public const TYPE = 'INVALID_SLUG';
+
     public static function fromSlug(string $slug, ?string $domain): self
     {
         $suffix = '';
@@ -15,6 +24,13 @@ class NonUniqueSlugException extends InvalidArgumentException
             $suffix = sprintf(' for domain "%s"', $domain);
         }
 
-        return new self(sprintf('Provided slug "%s" is not unique%s.', $slug, $suffix));
+        $e = new self(sprintf('Provided slug "%s" is already in use%s.', $slug, $suffix));
+
+        $e->detail = $e->getMessage();
+        $e->title = self::TITLE;
+        $e->type = self::TYPE;
+        $e->status = StatusCodeInterface::STATUS_BAD_REQUEST;
+
+        return $e;
     }
 }

module/Core/test/Exception/NonUniqueSlugExceptionTest.php

@@ -22,12 +22,12 @@ class NonUniqueSlugExceptionTest extends TestCase
     public function provideMessages(): iterable
     {
         yield 'without domain' => [
-            'Provided slug "foo" is not unique.',
+            'Provided slug "foo" is already in use.',
             'foo',
             null,
         ];
         yield 'with domain' => [
-            'Provided slug "baz" is not unique for domain "bar".',
+            'Provided slug "baz" is already in use for domain "bar".',
             'baz',
             'bar',
         ];