I would say no harm done. Plants have methods of mending themselves. You can fill the hole up with a can of " black foam" which is used in the construction of garden ponds or any foam gap filler will do. Just spray a bit in and after it expands and sets shave down the excess.

Personally I'd be concerned about a hole that size particularly as it looks as if the wood is rotting around it. I'm not sure what the solution is, hopefully Bamboo who is very knowledgable will be able to advise.