Hello! I need help with flycheck setup. If anybody knows how to solve this problem please let me know. Many thanks!

I wanna enable sh-posix-dash and sh-posix-dash checkers, but when I press C-u C-c ! x (in *Flycheck checkers*) I obtain x is undefined or X is undefined. I don't understand why it happens.

Note that: *Flycheck checkers* buffer is opened via M-x flycheck-verify-setup.

Flycheck version: 33snapshot (package: 20220729.1039)                                                                                          
Emacs version:    28.1                                                                                                                         
System:           x86_64-pc-linux-gnu                                                                                                          
Window system:    nil

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# Best regards, Emily Grace Seville.
[contacts]
phone = "+79245201384"