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

This reverts commit 38aac09151.

lua/nvim-tree/renderer/decorator/diagnostics.lua

@@ -33,22 +33,20 @@ local ICON_KEYS = {
 }
 
 ---@class (exact) DecoratorDiagnostics: Decorator
----@field icons HighlightedString[]?
+---@field icons HighlightedString[]
 local DecoratorDiagnostics = Decorator:new()
 
----Static factory method
 ---@param opts table
 ---@param explorer Explorer
 ---@return DecoratorDiagnostics
-function DecoratorDiagnostics:create(opts, explorer)
-  ---@type DecoratorDiagnostics
-  local o = {
+function DecoratorDiagnostics:new(opts, explorer)
+  local o = Decorator.new(self, {
     explorer = explorer,
     enabled = opts.diagnostics.enable,
     hl_pos = HL_POSITION[opts.renderer.highlight_diagnostics] or HL_POSITION.none,
     icon_placement = ICON_PLACEMENT[opts.renderer.icons.diagnostics_placement] or ICON_PLACEMENT.none,
-  }
-  o = self:new(o) --[[@as DecoratorDiagnostics]]
+  })
+  ---@cast o DecoratorDiagnostics
 
   if not o.enabled then
     return o