@boostpack/error

Utilities for working with errors in TypeScript.

Installation

npm install @boostpack/error

API

toError(error: unknown): Error

Safely converts any unknown value to an Error instance.

When useUnknownInCatchVariables is enabled (included in strict mode), TypeScript types catch variables as unknown instead of any. This makes direct access to .message or .stack a type error:

try {
  await someOperation();
} catch (e) {
  console.error(e.message); // TS18046: 'e' is of type 'unknown'
}

toError provides a safe and ergonomic way to handle this:

import { toError } from '@boostpack/error';

try {
  await someOperation();
} catch (e) {
  const error = toError(e);
  console.error(error.message);
}

// or inline
try {
  await someOperation();
} catch (e) {
  logger.error(toError(e).message);
}

Behavior:

• Error instance — returned as-is (including subclasses like TypeError)
• Other values — wrapped in new Error() with JSON-serialized representation; original value is preserved in error.cause
• Non-serializable values (circular references) — wrapped with a fallback message; original value is still available via error.cause

const result = toError({ code: 'TIMEOUT' });
result.message; // 'Unknown error: {"code":"TIMEOUT"}'
result.cause;   // { code: 'TIMEOUT' } — original value

License

MIT