1000 indicates a normal closure, meaning that the purpose for
which the connection was established has been fulfilled.
...
1005
1005 is a reserved value and MUST NOT be set as a status code in a
Close control frame by an endpoint. It is designated for use in
applications expecting a status code to indicate that no status
code was actually present.
https://www.rfc-editor.org/rfc/rfc6455.html#section-7.4.1
1000
...
1005