`bitcoin_core_sv2`: needs a cleanup/sanitize on error types

[plebhash]

some error types are being returned in a nonsensical way

for example:

sv2-apps/bitcoin-core-sv2/src/unix_capnp/v30x/template_distribution_protocol/mod.rs

Lines 424 to 431 in f817c49

	fn current_template_ids(&self) -> Result<HashSet<u64>, BitcoinCoreSv2TDPError> {
	let template_data_guard = self.template_data.read().map_err(|e| {
	error!("Failed to acquire read lock on template_data: {:?}", e);
	BitcoinCoreSv2TDPError::FailedToSendNewTemplateMessage
	})?;
	Ok(template_data_guard.keys().copied().collect())
	}