fix(dap.hover): clean up constructors

lua/ow/dap/hover/node.lua

@@ -11,15 +11,13 @@ Node.__index = Node
 ---@param parent ow.dap.hover.Node?
 ---@return ow.dap.hover.Node
 function Node.new(item, parent)
-    local node = setmetatable({
+    return setmetatable({
         item = item,
         parent = parent,
         children = {},
         is_expanded = false,
         is_last_child = false,
     }, Node)
-
-    return node
 end
 
 ---@return boolean

lua/ow/dap/hover/window.lua

@@ -20,7 +20,10 @@ local instance = nil
 
 ---@return ow.dap.hover.Window
 function Window.get_instance()
-    if not instance then
+    if instance then
+        return instance
+    end
+
     instance = setmetatable({
         max_width = nil,
         max_height = nil,
@@ -28,7 +31,6 @@ function Window.get_instance()
         bufnr = nil,
         augroup = nil,
     }, Window)
-    end
 
     return instance
 end