I need TDictionary<> in project.

As soon I add to System.Generics.Collections in uses of one of the forms(no matter is it main form or any other) I get error while loading application in browser. (Chrome, Edge, Brave)

Uncaught TypeError: Cannot set property 'eltype' of undefined
at Object.$intfcode (system.pas:101)
at Object.loadintf (rtl.js:186)
at (rtl.js:137)
at Index.html:101

Removing Unit from uses returns everything back to working condition.

This doesn't happen in simple project with one form.
I don't want to disassemble whole app to find to witch library it conflicts as I already have pretty much forms in it.

Can you help with it?

I have not encountered this so far.
Do you have more details how to reproduce this?

Only I can say yet is.

exception happens on this line :
generic TArray = array of T;
in unit System; file.

I can send project in private message if it makes any sense?

If you could isolate this and send it, then we can investigate or have this checked by the pas2js team.

Sent to support email.