HF RL Explorer

Remove onError and setOnError from ApolloLink

Remove onError and setOnError from ApolloLink: a task in LegoFlow-SWE (Harbor dataset). The ApolloLink class currently exposes two undocumented methods: onError and setOnError . These are confusing and only used internally by MockLink to rewrite errors. They should be removed entirely.

The task

The `ApolloLink` class currently exposes two undocumented methods: `onError` and `setOnError`. These are confusing and only used internally by `MockLink` to rewrite errors. They should be removed entirely.

Part of Lego-X/LegoFlow-SWE.