`execute if blocks` doesn't recognize subcommands after it

When trying to use command

`execute if blocks ~ ~1 ~ ~ ~1 ~ ~ ~2 ~ all run say hi`

The command validator says that the "run say hi" section is invalid. However, if you ignore it and run the command, it works as intended and says "hi" if the two blocks above the executor are both the same.

The problem appears to be that the `if blocks` subcommand doesn't recognize any further subcommands after it.