Summary

The documentation states that

Litestar handles all errors by default by transforming them into JSON responses.

Since #2131 this is not entirely true as exceptions will retain the MediaType of the route handler.

Consider the following endpoint:

@get(sync_to_thread=False)
def handler(q: int) -> str:
    raise ValueError

The MediaType of this handler will be MediaType.TEXT by default.
When let's say a ValidationException is raised due to wrong/missing query param or an internal error is raised, etc. the resulting response will be a JSON error message but in the response the content-type header will be set to text/plain.

If a client expects JSON on errors --by for example checking the status code-- as declared in the documentation, then JSON parsing might fail as the response content-type header does not indicate JSON.