fix(#80): loader asset plugin initialize_loader raising error

[davidw-carta]

Description

litestar-vite == 0.13.1 introduces a regression.
Running under production mode, say with gunicorn utilizing Jinja templates code such as

    {% if vite %}
      {{ vite("src/test.ts") | safe }}
    {% endif %}

Raises an exception ImproperlyConfiguredException 500 Error

full trace

[2025-04-04 16:06:15 -0700] [26044] [INFO] Application startup complete.
ERROR - 2025-04-04 16:06:16,732 - litestar - config - Uncaught exception (connection_type=http, path=/):
Traceback (most recent call last):
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/middleware/_internal/exceptions/middleware.py", line 158, in __call__
    await self.app(scope, receive, capture_response_started)
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/_asgi/asgi_router.py", line 100, in __call__
    await asgi_app(scope, receive, send)
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/routes/http.py", line 81, in handle
    response = await self._get_response_for_request(
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        scope=scope, request=request, route_handler=route_handler, parameter_model=parameter_model
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/routes/http.py", line 133, in _get_response_for_request
    return await self._call_handler_function(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        scope=scope, request=request, parameter_model=parameter_model, route_handler=route_handler
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/routes/http.py", line 157, in _call_handler_function
    response: ASGIApp = await route_handler.to_response(
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        app=scope["litestar_app"], data=response_data, request=request
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/handlers/http_handlers/base.py", line 584, in to_response
    return await response_handler(app=app, data=data, request=request)  # type: ignore[call-arg]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/handlers/http_handlers/_utils.py", line 152, in handler
    return response.to_asgi_response(  # type: ignore[no-any-return]
           ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        app=None,
        ^^^^^^^^^
    ...<6 lines>...
        type_encoders=type_encoders,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/response/template.py", line 149, in to_asgi_response
    body = template.render(**context).encode(self.encoding)
           ~~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/jinja2/environment.py", line 1295, in render
    self.environment.handle_exception()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/jinja2/environment.py", line 942, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "/Users/davidw/Dev/work/bug/my_app/app/templates/index.html", line 9, in top-level template code
    {{ vite("src/test.ts") | safe }}
    ^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar_vite/loader.py", line 61, in render_asset_tag
    ).asset_loader.render_asset_tag(path, scripts_attrs)
                   ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar_vite/loader.py", line 144, in render_asset_tag
    "".join([self.generate_asset_tags(p, scripts_attrs=scripts_attrs) for p in path]),
             ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar_vite/loader.py", line 271, in generate_asset_tags
    raise ImproperlyConfiguredException(
    ...<3 lines>...
    )
litestar.exceptions.http_exceptions.ImproperlyConfiguredException: 500: Cannot find %s in Vite manifest at %s.  Did you forget to build your assets after an update? ['src/test.ts'] public/manifest.json
ERROR - 2025-04-04 16:23:16,576 - litestar - config - Uncaught exception (connection_type=http, path=/):
Traceback (most recent call last):
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/middleware/_internal/exceptions/middleware.py", line 158, in __call__
    await self.app(scope, receive, capture_response_started)
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/_asgi/asgi_router.py", line 100, in __call__
    await asgi_app(scope, receive, send)
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/routes/http.py", line 81, in handle
    response = await self._get_response_for_request(
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        scope=scope, request=request, route_handler=route_handler, parameter_model=parameter_model
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/routes/http.py", line 133, in _get_response_for_request
    return await self._call_handler_function(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        scope=scope, request=request, parameter_model=parameter_model, route_handler=route_handler
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/routes/http.py", line 157, in _call_handler_function
    response: ASGIApp = await route_handler.to_response(
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        app=scope["litestar_app"], data=response_data, request=request
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/handlers/http_handlers/base.py", line 584, in to_response
    return await response_handler(app=app, data=data, request=request)  # type: ignore[call-arg]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/handlers/http_handlers/_utils.py", line 152, in handler
    return response.to_asgi_response(  # type: ignore[no-any-return]
           ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        app=None,
        ^^^^^^^^^
    ...<6 lines>...
        type_encoders=type_encoders,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar/response/template.py", line 149, in to_asgi_response
    body = template.render(**context).encode(self.encoding)
           ~~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/jinja2/environment.py", line 1295, in render
    self.environment.handle_exception()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/jinja2/environment.py", line 942, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "/Users/davidw/Dev/work/bug/my_app/app/templates/index.html", line 9, in top-level template code
    {{ vite("src/test.ts") | safe }}
    ^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar_vite/loader.py", line 61, in render_asset_tag
    ).asset_loader.render_asset_tag(path, scripts_attrs)
                   ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar_vite/loader.py", line 144, in render_asset_tag
    "".join([self.generate_asset_tags(p, scripts_attrs=scripts_attrs) for p in path]),
             ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/davidw/Dev/work/bug/.venv/lib/python3.13/site-packages/litestar_vite/loader.py", line 271, in generate_asset_tags
    raise ImproperlyConfiguredException(
    ...<3 lines>...
    )
litestar.exceptions.http_exceptions.ImproperlyConfiguredException: 500: Cannot find %s in Vite manifest at %s.  Did you forget to build your assets after an update? ['src/test.ts'] public/manifest.json

Let me know if you want a full reproducible examle

Closes

[matthew-carta]

Seems to be introduced with the singleton base class here:
v0.13.0...v0.13.1#diff-5fac0b71b0ac3f64cbcb36eff6dfab022f2603603c13704f85ef96802fa5dee7L79-R107

[cofin]

Sorry for the long delay on this. Thanks for the PR here.