Ngx-translate unused keys detection tool?

I’m pretty sure that I may have 3 or 5 keys in my json ngx-translate translation files which aren’t used anymore in my app (don’t judge me).

Since size of the app = boot time, I would like to try to find them without having to go thru all my keys manually (I know I gonna save maybe 14 bytes, but still, smaller bundle, faster load)

Does someone knows a script or tool library or whatever which would help to achieve this in a fast way?

Up and posted to stackoverflow too…