Better error handling with unknown type in TypeScript

main.ts

const hasErrorCode = (error: unknown): error is { code: string } => {
  return !!error && typeof error === 'object' && 'code' in error && typeof error.code === 'string';
};

try {
  throw {code: 72};
} catch (error: unknown) {
  if (hasErrorCode(error)) {
    console.error(`Failed with error code "${error.code}".`);
  }
}