bug: fix loader asset plugin initialize_loader ImproperlyConfiguredException 500 Error

Author: davidw-carta

src/py/litestar_vite/loader.py

@@ -104,7 +104,9 @@ def initialize_loader(cls, config: "ViteConfig") -> "ViteAssetLoader":
         Returns:
             The manifest loader.
         """
-        return cls(config=config)
+        _cls = cls(config=config)
+        _cls.parse_manifest()
+        return _cls
 
     @cached_property
     def version_id(self) -> str: