Fix: Don't pollute global namespace with option vars.

Use `get()` since options are only used once. and add abort
to functions.

Thanks to (u/LucHermitte):
https://www.reddit.com/r/vim/comments/j27gi7/just_made_my_first_plugin_vimbettergrep/g746cut/?utm_source=reddit&utm_medium=web2x&context=3

Author: qalshidi

autoload/bettergrep.vim

@@ -18,7 +18,7 @@ endif
 
 if exists("*jobstart")                " NeoVim async method
 
-  function! bettergrep#Grep(cmd, ...)
+  function! bettergrep#Grep(cmd, ...) abort
 
     let s:cmd = a:cmd
 
@@ -47,7 +47,7 @@ else                                  " regular blocking method
   " Thanks to RomainL's gist
   " https://gist.github.com/romainl/56f0c28ef953ffc157f36cc495947ab3
 
-  function! bettergrep#Grep(cmd, ...)
+  function! bettergrep#Grep(cmd, ...) abort
       execute a:cmd . " " . "system(join([g:bettergrepprg] + [expandcmd(join(a:000, ' '))], ' '))"
   endfunction
 

plugin/bettergrep.vim

@@ -8,27 +8,19 @@ if exists('g:bettergrep_loaded')
 endif
 let g:bettergrep_loaded = 1
 
-" Options
-if !exists('g:bettergrep_no_mappings')
-  let g:bettergrep_no_mappings = 0
-endif
-if !exists('g:bettergrep_no_abbrev')
-  let g:bettergrep_no_abbrev = 0
-endif
-
 " Commands
 command! -nargs=+ -complete=file_in_path -bar Grep     call bettergrep#Grep('cgetexpr', <f-args>)
 command! -nargs=+ -complete=file_in_path -bar LGrep    call bettergrep#Grep('lgetexpr', <f-args>)
 command! -nargs=+ -complete=file_in_path -bar Grepadd  call bettergrep#Grep('caddexpr', <f-args>)
 command! -nargs=+ -complete=file_in_path -bar LGrepadd call bettergrep#Grep('laddexpr', <f-args>)
 
 " Mappings
-if !g:bettergrep_no_mappings
+if !get(g:, 'bettergrep_no_mappings', 0)
   nnoremap <C-g> :Grep 
 endif
 
 " Abbreviations
-if !g:bettergrep_no_abbrev
+if !get(g:, 'bettergrep_no_abbrev', 0)
   cnoreabbrev <expr> gr        (getcmdtype() ==# ':' && getcmdline() ==# 'gr')  ? 'Grep'  : 'gr'
   cnoreabbrev <expr> lgr       (getcmdtype() ==# ':' && getcmdline() ==# 'lgr') ? 'LGrep' : 'lgr'
   cnoreabbrev <expr> gre       (getcmdtype() ==# ':' && getcmdline() ==# 'gre')  ? 'Grep'  : 'gre'