fix: highlighting is lost when colorscheme is changed

[habamax]

New vim restores default highlight links, but fails to do it when there is no default link in the first place.

Without this fix, vim-exchange looses highlighting after :colorscheme ...

Relates to vim/vim#6970

[tommcdo]

Did you verify that this fixes the issue? It seems that the line you're adding is already being called at startup:

vim-exchange/plugin/exchange.vim

Lines 335 to 339 in e797a21

	command! -bar XchangeHighlightToggle call s:highlight_toggle()
	command! -bar XchangeHighlightEnable call s:highlight_toggle(1)
	command! -bar XchangeHighlightDisable call s:highlight_toggle(0)
	XchangeHighlightEnable

vim-exchange/plugin/exchange.vim

Lines 232 to 239 in e797a21

	function! s:highlight_toggle(...)
	if a:0 == 1
	let s:enable_highlighting = a:1
	else
	let s:enable_highlighting = !s:enable_highlighting
	endif
	execute 'highlight link _exchange_region' (s:enable_highlighting ? 'ExchangeRegion' : 'None')
	endfunction

[habamax]

Sure I did.

Note default added.

[tommcdo]

Yep, I see it now

[tommcdo]

Thanks!