fix: create alias only for classes that do not exist. (#1269)

* fix: create alias only for classes that do not exist.

* style: apply styleci.

Author: lalcebo

src/Application.php

@@ -790,7 +790,9 @@ public function withAliases($userAliases = [])
             $merged = array_merge($defaults, $userAliases);
 
             foreach ($merged as $original => $alias) {
-                class_alias($original, $alias);
+                if (! class_exists($alias)) {
+                    class_alias($original, $alias);
+                }
             }
         }
     }