fix(diagnostic): handle an unknown or missing client (#16242)

gpanders · web-flow · commit 1fdbd29dfa63 · 2021-11-05T10:10:27.000-06:00
Sometimes plugins use pseudo-client IDs (e.g. nvim-lint or null-ls) in
order to hook into the LSP infrastructure without being a bona fide LSP
client. In these cases, get_client_by_id() will return nil since the
client ID given does not correspond to a real client recognized by the
LSP subsystem. When this happens, use "unknown" for the client name.
diff --git a/runtime/lua/vim/lsp/diagnostic.lua b/runtime/lua/vim/lsp/diagnostic.lua
@@ -147,7 +147,7 @@ function M.get_namespace(client_id)
   vim.validate { client_id = { client_id, 'n' } }
   if not _client_namespaces[client_id] then
     local client = vim.lsp.get_client_by_id(client_id)
-    local name = string.format("vim.lsp.%s.%d", client.name, client_id)
+    local name = string.format("vim.lsp.%s.%d", client and client.name or "unknown", client_id)
     _client_namespaces[client_id] = vim.api.nvim_create_namespace(name)
   end
   return _client_namespaces[client_id]
