Passing --trace probably won’t do you much good in this case. If you could share the project that would be the fastest way to a resolution.
Otherwise, you can try to open Terminal/CMD, open the project root folder and execute uno build -vv command. It should throw some useful information there.
I think you can just get rid of the line <ModalJS ux:Global="Modal" /> and the project should be working alright. The require() in JS should be enough for the modals to work.