s:strip(string) not working on neovim

[lazywhite]

my vim version info

 # vim --version
NVIM v0.5.0
Build type: RelWithDebInfo
LuaJIT 2.1.0-beta3
Compilation: /usr/bin/gcc-11 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 -DNVIM_TS_HAS_SET_MATCH_LIMIT -O2 -g -Og -g -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fno-common -fdiagnostics-color=always -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -DMIN_LOG_LEVEL=3 -I/home/runner/work/neovim/neovim/build/config -I/home/runner/work/neovim/neovim/src -I/home/runner/work/neovim/neovim/.deps/usr/include -I/usr/include -I/home/runner/work/neovim/neovim/build/src/nvim/auto -I/home/runner/work/neovim/neovim/build/include
Compiled by runner@fv-az242-526

Features: +acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "
/home/runner/work/neovim/neovim/build/nvim.AppDir/usr/share/nvim"

Run :checkhealth for more info

filetypes/c.vim

here is a working example on my laptop, but when I change trim(str) to s:strip(str), it's not working

" c behaves like so:  if it's pre-processing, do nothing
function! filetypes#c#parse()
    if trim(b:currentLine) =~ "^#"
        let b:wasExtensionExecuted = 1
        return
    endif
endfunction