fix(#2154): find_file doesn't work when group_empty option is enabled (#2100)

Co-authored-by: Alexander Courtis <alex@courtis.org>

lua/nvim-tree/lib.lua

@@ -81,7 +81,6 @@ function M.get_last_group_node(node)
 end
 
 function M.expand_or_collapse(node)
-  node.open = not node.open
   if node.has_children then
     node.has_children = false
   end
@@ -90,6 +89,9 @@ function M.expand_or_collapse(node)
     core.get_explorer():expand(node)
   end
 
+  node = M.get_last_group_node(node)
+  node.open = not node.open
+
   renderer.draw()
 end