feat: warn if quarto resource path is not found

closes nvim-lua#36

Author: jmbuhr

lua/plugins/quarto.lua

@@ -299,10 +299,14 @@ return {
       end
 
       local lua_library_files = vim.api.nvim_get_runtime_file("", true)
-      local resource_path = get_quarto_resource_path()
-      table.insert(lua_library_files, resource_path .. '/lua-types')
       local lua_plugin_paths = {}
-      table.insert(lua_plugin_paths, resource_path .. '/lua-plugin/plugin.lua')
+      local resource_path = get_quarto_resource_path()
+      if resource_path == nil then
+        vim.notify_once("quarto not found, lua library files not loaded")
+      else
+        table.insert(lua_library_files, resource_path .. '/lua-types')
+        table.insert(lua_plugin_paths, resource_path .. '/lua-plugin/plugin.lua')
+      end
 
       -- not upadated yet in automatic mason-lspconfig install,
       -- open mason manually with `<space>vm` and `/` search for lua.