Translation: "You screwed up somewhere in this entire file. Figure it out yourself. Good luck! 🤷”

It's the "Segmentation fault” of the modern era.

i’m unable to type-check YOUR expression in reasonable time
(The actual problem, 67 lines below the error message: .disabled() needs to be applied to the Button, not the ToolbarItem, which I had to figure out by just commenting out random stuff until it compiled.)
@marcoarment this is all very much plausible and warranted for.