Function isErr

isErr<T, E>(val): val is ErrResult<never, E>
Type guard to check if a Result is an Err value. This function is used to narrow down the type of a Result to ErrResult in TypeScript type system.
Type Parameters
- T extends NonUndefined
- E extends NonUndefined
Parameters
- val: Result<T, E>
  The Result to be checked.
Returns val is ErrResult<never, E>
true if the provided Result is an ErrResult, false otherwise.

Example
```
const result = Err('Failure');
if (isErr(result)) {
  console.log('Operation failed with error:', result.unwrapErr());
}
```
Deprecated
Use Result.isErr instead.
- Defined in result/result.ts:447