Error detected while processing - Invalid argument

## Before submitting your issue（请在提交 issue 前一定要检查以下项目！）

1. Update to the latest version of CtrlSF.
2. Update your backend(ag/ack/pt/rg) to their latest version.
3. Enable debug mode to try to find what is going wrong yourself. You can enable debug mode by `let g:ctrlsf_debug_mode = 1`.

If you can't find out why things do not work or can be sure it's a bug of CtrlSF, please fulfill below issue template. Thanks in advance!

## Issue template

#### Issue description

Error detected while processing /home/sikm/.vim/plugged/ctrlsf.vim/autoload/ctrlsf.vim:
line 20:
E475: Invalid argument: args, override = v:false) abort
line 23:
E121: Undefined variable: a:override
E116: Invalid arguments for function 42_Reset
line 28:
E133: :return not inside a function
line 20:
E475: Invalid argument: args, override = v:false) abort
line 23:
E121: Undefined variable: a:override
E116: Invalid arguments for function 42_Reset
line 26:
E121: Undefined variable: a:args
E116: Invalid arguments for function ctrlsf#opt#ParseOptions
line 28:
E133: :return not inside a function
line 20:
E475: Invalid argument: args, override = v:false) abort
line 23:
E121: Undefined variable: a:override
E116: Invalid arguments for function 42_Reset
line 26:
E121: Undefined variable: a:args
E116: Invalid arguments for function ctrlsf#opt#ParseOptions
line 28:
E133: :return not inside a function
line 20:
E475: Invalid argument: args, override = v:false) abort
line 23:
E121: Undefined variable: a:override
E116: Invalid arguments for function 42_Reset
line 26:
E121: Undefined variable: a:args
E116: Invalid arguments for function ctrlsf#opt#ParseOptions
line 28:
E133: :return not inside a function
line 20:
E475: Invalid argument: args, override = v:false) abort
line 23:

#### Things about your system and environment（请在此填写你的系统信息）

| field | value |
|:-------:|:------------------------------------:|
| os | Ubuntu 18.04 LTS |
| vim | *VIM - Vi IMproved 8.0 (2016 Sep 12, compiled Apr 18 2023 09:20:34)* |
| backend | *ag 2.1.0* |
| locale | *en_US.UTF-8* |