Undefined variable s:chars_s

[w2kpro]

Vim 9.1 on Manjaro Linux (vim -f -u .vimrc-core) quick-scope installed using Plug Added "let g:qs_highlight_on_keys = ['f', 'F', 't', 'T']" to .vimrc-core Characters are highlighted, but when cursor is moved to a new line the following error occurs: Error detected while processing function quick_scope#HighlightLineDelayCallback[2]..quick_scope #HighlightLine[12]..<SNR>49_get_highlight_patterns[130]..<SNR>49_save_chars_with_secondary_high lights: line 6: E121: Undefined variable: s:chars_s