Errors

Every failure is a named program error. Translate it into a sentence that tells the user what to do next.

Handling

Never hardcode a numeric error code. Anchor assigns them by declaration order, so adding one variant shifts everything after it, and that has already happened twice. Match on the name through parseOtcError(), which returns { code, name, message } or null when the failure was not ours.

import { parseOtcError } from '@otcdex/sdk';

try {
  await sendAndConfirmTransaction(connection, tx, [wallet]);
} catch (err) {
  // Never show the raw simulation log to a user.
  const otc = parseOtcError(err);
  toast.error(otc ? otc.message : 'Transaction failed');
  // Worth re-quoting automatically on a moved price.
  if (otc?.name === 'PriceBoundExceeded' || otc?.name === 'ProceedsBelowMinimum') refresh();
}

Price bound errors are not bugs. They are the protection working: the order was re-priced between your quote and your transaction landing, and the program refused to execute at a worse price than you signed for. Re-quote and resubmit.

Reference

Anything unrecognised should fall back to a generic message plus the transaction signature. Do not print a simulation log into the interface: it is unreadable to a user and often leaks account addresses they did not ask about. Keep it in console.debug.