Request body: body is now cleared on errors. Previously, after errors the request body was left in a potentially inconsistent state, with r->headers_in.content_length_n which might be larger than buffers actually stored in r->request_body->bufs (or not set at all, in case of HTTP/2 and HTTP/3). This can cause issues if the request body is subsequently used during error_page handling, such as when proxying. Fix is to clear r->request_body->bufs if this happens, and set r->headers_in.content_length_n to 0, much like it happens when ngx_http_discard_request_body() is called when returning 413 from ngx_http_core_find_config_phase() for requests with Content-Length.