MC Ripper allows you to rip assets from pc java edition that are not in a resource pack or jar file. It rips them from ./minecraft/assets/objects. Then it converts it into a resource pack so if vanilla ever has any easter eggs resource packs you can rip them. I used this to rip the April fools resource pack
How to use:
1. open app
2. select json index file(not a version json!) go to %appdata%/.minecraft/assets/indexes/.json
yeah um I was using problematic code. If there are no json files for said resource objects mcmeta files it won't dynamically generate it. I don't have time to find a working solution atm since I have more important projects to do. It's due to the files not being inside of the objects indices folder. I don't know if they fixed rp in 1.13+ or not where if the files don't exist it uses the lower priority ones. Basically the missing resources are probably indside of another json folder or the mc jar Idk and someone else can figure out a solution and a modified jar.