Error with ffi:object in eval

[cxxxr]

open browser-repl

$ ros install valtan
$ cd example/browser-repl
$ npm i
$ npm run build
$ open index.html

in browser-repl

COMMON-LISP-USER> (ffi:object #j"foo" 100)
The function PUSH is undefined
Backtrace:
0: (COMMON-LISP::PRINT-BACKTRACE :STREAM #S(STRING-OUTPUT-STREAM :BUFFER ""))
1: (PUSH (FFI:CL->JS "foo") NIL)
2: (#<Function> (FFI:CL->JS "foo") 100)
3: (APPLY #<Function> ((FFI:CL->JS "foo") 100))
4: (COMPILER::PASS1-TOPLEVEL (FFI:OBJECT (FFI:CL->JS "foo") 100) T T)
5: (COMPILER:COMPILE-TOPLEVEL (FFI:OBJECT (FFI:CL->JS "foo") 100))
6: (EVAL (FFI:OBJECT (FFI:CL->JS "foo") 100))