Fix error navigation

I've seen when `flycheck-ignore-column` is `nil`, error navigation with `next-error` causes moving point one character too far and no message in the minibuffer.

An example:

```python
def a(): pass
def b(): pass
```

Try to navigate errors with ``C-x ` `` (with flake8 checker). No messages are displayed in the minibuffer.

This commit *should* fix it but I'm not sure if it is the desired behaviour.