fix(lsp): schedule removal of client object (#20148)

The execution of the LspDetach autocommands in the LSP client's on_exit
function are scheduled on the event loop to avoid making API calls in a
fast context; however, this means that by the time the LspDetach
autocommands finally run the client object has already been deleted.

To address this, we also schedule the deletion of the client on the
event loop so that it is guaranteed to occur after all of the LspDetach
autocommands have fired.

1 files changed, 22 insertions, 21 deletions

diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index 051127c9c6..22933d8143 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -1147,33 +1147,34 @@ function lsp.start_client(config)
 
           local namespace = vim.lsp.diagnostic.get_namespace(client_id)
           vim.diagnostic.reset(namespace, bufnr)
-        end)
 
-        client_ids[client_id] = nil
-      end
-      if vim.tbl_isempty(client_ids) then
-        vim.schedule(function()
-          unset_defaults(bufnr)
+          client_ids[client_id] = nil
+          if vim.tbl_isempty(client_ids) then
+            unset_defaults(bufnr)
+          end
         end)
       end
     end
-    local client = active_clients[client_id] and active_clients[client_id]
-      or uninitialized_clients[client_id]
-    active_clients[client_id] = nil
-    uninitialized_clients[client_id] = nil
 
-    -- Client can be absent if executable starts, but initialize fails
-    -- init/attach won't have happened
-    if client then
-      changetracking.reset(client)
-    end
-    if code ~= 0 or (signal ~= 0 and signal ~= 15) then
-      local msg =
-        string.format('Client %s quit with exit code %s and signal %s', client_id, code, signal)
-      vim.schedule(function()
+    -- Schedule the deletion of the client object so that it exists in the execution of LspDetach
+    -- autocommands
+    vim.schedule(function()
+      local client = active_clients[client_id] and active_clients[client_id]
+        or uninitialized_clients[client_id]
+      active_clients[client_id] = nil
+      uninitialized_clients[client_id] = nil
+
+      -- Client can be absent if executable starts, but initialize fails
+      -- init/attach won't have happened
+      if client then
+        changetracking.reset(client)
+      end
+      if code ~= 0 or (signal ~= 0 and signal ~= 15) then
+        local msg =
+          string.format('Client %s quit with exit code %s and signal %s', client_id, code, signal)
         vim.notify(msg, vim.log.levels.WARN)
-      end)
-    end
+      end
+    end)
   end
 
   -- Start the RPC client.