Function err

err<T>(error: string): Result<T>
Creates a new Err instance representing a failed operation.
Type Parameters
- T
  The type that would have been returned if successful
Parameters
- error: string
  The error message describing what went wrong
Returns Result<T>
A Result containing the error message
Example
```
const result = JsonDecoder.err<number>("Invalid number");
// result = Err("Invalid number")
```