Description of the Issue

The error detection on Regex searches in the find box doesn't warn the lack of a close parenthesis when the search string is Greek characters.

Steps to Reproduce the Issue

Select Find from Search menu
type " (Παυσ " [accidentally leaving out close paren]
2. Click Find Next
3. Sudden death.

Expected Behavior

Error message "invalid regular expression"

Actual Behavior

Notepad shuts down, all unsaved edits lost.

Debug Information

Notepad++ v8.1.5 (64-bit)
Build time : Sep 26 2021 - 15:23:23
Path : C:\Program Files\Notepad++\notepad++.exe
Command Line :
Admin mode : OFF
Local Conf mode : OFF
Cloud Config : OFF
OS Name : Windows 10 Home (64-bit)
OS Version : 1909
OS Build : 18363.1556
Current ANSI codepage : 1252
Plugins : DSpellCheck.dll mimeTools.dll NppConverter.dll NppExport.dll