BasePresenter_onError.kt

...
    @CallSuper
    open fun onError(throwable: Throwable) {
        when (throwable) {
            is HttpException -> {
                val responseBody = throwable.response().errorBody().string()

                try {
                    val serverException = parseError(responseBody)
                    processServerException(serverError)
                } catch (e: JsonSyntaxException) {
                    viewState.showError(R.string.unexpected_server_error)
                }
            }

            is IOException -> viewState.showError(R.string.common_network_error)

            else -> {
                val errorMessage = throwable.message ?: getString(R.string.common_unexpected_error)
                viewState.showError(errorMessage)
            }
        }

        viewState.hideProgress()
    }
...