rust-analyzer sometimes returns a hover result with language being
"text", but there's no syntax/text.vim, so this would fail with:
Error detected while processing function <SNR>150_VimOutputCallback[6]..<lambda>8[1]..ale#lsp#HandleMessage[30]..ale#hover#HandleLSPResponse[42]..ale#floating_preview#Show[13]..<SNR>161_VimShow:
line 13:
E484: Cannot open file syntax/text.vim
Only including the file when it actually exists fixes this.