Don't deprecate `code` error field

support/doc/api/openapi.yaml

@@ -53,7 +53,7 @@ info:
     }
     ```
 
-    We provide error `type` values for [a growing number of cases](https://github.com/Chocobozzz/PeerTube/blob/develop/packages/models/src/server/core-error-code.enum.ts),
+    We provide error `type` values for [a growing number of cases](https://github.com/Chocobozzz/PeerTube/blob/develop/packages/models/src/server/server-error-code.enum.ts),
     but it is still optional. Types are used to disambiguate errors that bear the same status code
     and are non-obvious:
 
@@ -109,7 +109,6 @@ info:
 
     Some fields could be included with previous versions. They are still included but their use is deprecated:
     - `error`: superseded by `detail`
-    - `code`: superseded by `type` (which is now an URI)
 
     # Rate limits