fix(#2945): stack overflow on api.git.reload or fugitive event with watchers disabled (#2949)

* Reapply "refactor(#2871, #2886): multi instance: node classes created (#2916)"

This reverts commit 50e919426a.

* fix(#2945): stack overflow on api.git.reload or fugitive event

lua/nvim-tree/actions/moves/sibling.lua

@@ -15,7 +15,7 @@ function M.fn(direction)
     local first, last, next, prev = nil, nil, nil, nil
     local found = false
     local parent = node.parent or core.get_explorer()
-    Iterator.builder(parent.nodes)
+    Iterator.builder(parent and parent.nodes or {})
       :recursor(function()
         return nil
       end)