Editor was attempting to delete non-existent chars which is UB. Fixed by
checking before deleting. Also fixed was a problem created by having to
press enter to change the search string which advanced the selection to
the first match. In the next step one would expect that pressing enter
on the replace field would replace the selected item but was replacing
the item found after he first.
This was fixed by always replacing the current selection first. If the
replacement is the same as the searched term then replacing won't
advance the cursor, but if they are different then the current match
will no longer exist so it would search fora new one.
<!--
Please provide as much information as possible about what your PR aims
to do.
PRs with no description will most likely be closed until more
information is provided.
If you're planing on changing fundamental behaviour or add big new
features, please open a GitHub Issue first before starting to work on
it.
If it's not something big and you still want to contact us about it,
feel free to do so !
-->
### Problem description
<!-- Describe the bug that you fixed/feature request that you
implemented, or link to an existing issue describing it -->
### Implementation description
<!-- Explain what you did to correct the problem -->
### Screenshots
<!-- If your change is visual, take a screenshot showing it. Ideally,
make before/after sceenshots -->
### Additional things
<!-- Anything else you would like to say -->
Co-authored-by: Nik <werwolv98@gmail.com>