Remove property, update error message

src/Twig/Component/Badge.php

@@ -14,8 +14,6 @@ final class Badge
 {
     public string $finalClasses;
 
-    private ?string $colour;
-
     public function __construct(private string $baseClasses)
     {
     }
@@ -41,7 +39,7 @@ final class Badge
         } else {
 
             if (null === $object) {
-                throw new \RuntimeException("You must specify a badge colour If no instance of BadgeableInterface is provided.");
+                throw new \RuntimeException(sprintf("You must specify a colour for the badge if no instance of %s is provided.", BadgeableInterface::class));
             }
 
             $palette = $object->getBadgeColour()->getPalette();