LSP diagnostics verify attached client

lua/fzf-lua/providers/lsp.lua

@@ -290,6 +290,12 @@ end
 M.diagnostics = function(opts)
   opts = normalize_lsp_opts(opts, config.lsp)
 
+  local lsp_clients = vim.lsp.buf_get_clients(0)
+  if #lsp_clients == 0 then
+    utils.info("LSP: no client attached")
+    return
+  end
+
   local lsp_type_diagnostic = vim.lsp.protocol.DiagnosticSeverity
   local current_buf = vim.api.nvim_get_current_buf()