Variable ERROR_CODE_RpcMethodNotFoundErrorConst

This is presumably the equivalent of the HTTP 404 error

const ERROR_CODE_RpcMethodNotFoundError = -32601;

See https://github.com/aeternity/aepp-sdk-js/blob/1065da9a46b8dbfe60a2c3e5646e7422ee7e495e/src/aepp-wallet-communication/schema.ts#L211-L224