Fix empty autosuggestions bugging out the end key
Fix empty autosuggestions bugging out the end key

The `nc.end_of_line(event)` line was never triggered. During writing this,
the `Suggestion` class from prompt-toolkit has no `__bool__` implemented,
which meant its objects always evaluate to `True`, even if
`b.suggestion.text == ''`.

The above resulted in the end key being unusable after an
autosuggestion has been accepted by the user.

ipython/ipython,ipython/ipython