LSP: highlight groups test, doc

2 files changed, 28 insertions, 11 deletions

diff --git a/runtime/doc/lsp.txt b/runtime/doc/lsp.txt
index 70a3110042..c173ecead3 100644
--- a/runtime/doc/lsp.txt
+++ b/runtime/doc/lsp.txt
@@ -57,24 +57,39 @@ use of |v:lua| to call Lua from Vimscript): >
   autocmd Filetype python setlocal omnifunc=v:lua.vim.lsp.omnifunc
 
 
-FAQ ~
-
-> How to force-reload LSP?
+================================================================================
+FAQ                                                     *lsp-faq*
 
-Stop all clients, then reload the buffer. >
+- Q: How to force-reload LSP?
+  A: Stop all clients, then reload the buffer. >
 
   :lua vim.lsp.stop_all_clients()
   :edit
 
-> Why isn't completion working?
-
-In the buffer where you want to use LSP, check that 'omnifunc' is set to
-"v:lua.vim.lsp.omnifunc": >
+- Q: Why isn't completion working?
+  A: In the buffer where you want to use LSP, check that 'omnifunc' is set to
+  "v:lua.vim.lsp.omnifunc": >
 
   :verbose set omnifunc?
 
-Some other plugin may be overriding the option. To avoid that, you could set
-the option in an |after-directory| ftplugin, e.g. "after/ftplugin/python.vim".
+<  Some other plugin may be overriding the option. To avoid that, you could
+  set the option in an |after-directory| ftplugin, e.g.
+  "after/ftplugin/python.vim".
+
+================================================================================
+LSP HIGHLIGHT                                           *lsp-highlight*
+
+When LSP is activated these highlight groups are defined:
+
+  LspDiagnosticsError
+  LspDiagnosticsHint
+  LspDiagnosticsInformation
+  LspDiagnosticsUnderline
+  LspDiagnosticsUnderlineError
+  LspDiagnosticsUnderlineHint
+  LspDiagnosticsUnderlineInformation
+  LspDiagnosticsUnderlineWarning
+  LspDiagnosticsWarning
 
 ================================================================================
 LSP API                                                 *lsp-api*
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 338aedb4e0..df82e2d412 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -549,7 +549,9 @@ do
   local underline_highlight_name = "LspDiagnosticsUnderline"
   vim.cmd(string.format("highlight default %s gui=underline cterm=underline", underline_highlight_name))
   for kind, _ in pairs(protocol.DiagnosticSeverity) do
-    vim.cmd(string.format("highlight default link %s%s %s", underline_highlight_name, kind, underline_highlight_name))
+    if type(kind) == 'string' then
+      vim.cmd(string.format("highlight default link %s%s %s", underline_highlight_name, kind, underline_highlight_name))
+    end
   end
 
   local severity_highlights = {}