fix(rpc): fix websocket subscription panic when no closing error

[srene]

PR Standards

Opening a pull request should be able to meet the following requirements

In case RPC websocket is closed with an error that is not websocket.CloseError, UnsubscribeAll is not called. This causes the service may try to write to a closed channel, when the error happens and the websocket is closed.

This PR basically calls UnsubscribeAll when any error

PR naming convention: https://hackmd.io/@nZpxHZ0CT7O5ngTp0TP9mg/HJP_jrm7A

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Close #1043

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For Author:

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For Reviewer:

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After reviewer approval:

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