The Result to unwrap.
The error value if Result.Err, otherwise undefined.
const okResult = Result.ok('data');
const errResult = Result.err('problem');
// Result.unwrapErr returns undefined for Ok results
// eslint-disable-next-line @typescript-eslint/no-confusing-void-expression
assert(Result.unwrapErr(okResult) === undefined);
// Result.unwrapErr returns the error value for Err results
assert(Result.unwrapErr(errResult) === 'problem');
Unwraps a
Result, returning the error value orundefinedif it isResult.Ok.This provides a safe way to extract error values from Results without throwing exceptions. Useful for error handling patterns where you want to check for specific error conditions.