[Bug] PanelMenu template prop type issue

[olbe-solvve]

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CodeSandbox Case (Bug Reports)
https://codesandbox.io/s/nervous-darkness-rhx7g

Current behavior
spamming with warning about wrong prop type in the internal lib component

Expected behavior
no Vue warnings in the console

Minimal reproduction of the problem with instructions
after using Panel menu with templating feature Vue throws a warning to the console like this one

Invalid prop: type check failed for prop "template". Expected Object, got Function  
  at <PanelMenuSub model= [] class="p-panelmenu-root-submenu" template=fn<renderFnWithContext>  ... > 
  at <BaseTransition appear=false persisted=false mode=undefined  ... > 
  at <Transition name="p-toggleable-content" > 
  at <PanelMenu class="panel-menu" model= (5) [{…}, {…}, {…}, {…}, {…}] expandedKeys= {GENERAL: true} >

Take a look at the console in this sandbox https://codesandbox.io/s/nervous-darkness-rhx7g?file=/src/App.vue

Please tell us about your environment:
Windows, Vs Code, webpack

• Vue version: 3.X
  3.0.0 with Typescript

• PrimeVue version: 3.4.X
  3.8.2

• Browser:
  all