window.location.href = 'some-valid-url' works, but then window.location.href = 'other-valid-url' breaks exokit's REPL

[shawwn]

To Reproduce
Steps or commands ran to reproduce the behavior:

$ node .
[x] window.location.href = 'https://ga-nksuawgghv.now.sh/'
... snip ...
[x] window.location.href = 'https://ga-ixedatnjya.now.sh/'
Thrown:
{ Error: cancel request: window destroyed
    at WorkerVm.window.destroy.destroy (/Users/emily/exokit-june/src/WindowVm.js:208:19)
    at WorkerVm.window.on (/Users/emily/exokit-june/src/WindowVm.js:183:12)
    at WorkerVm.emit (events.js:193:13)
    at WorkerVm.EventEmitter.emit (domain.js:481:20)
    at Worker._message (/Users/emily/exokit-june/src/WindowVm.js:39:16)
    at Worker.emit (events.js:193:13)
    at Worker.EventEmitter.emit (domain.js:481:20)
    at MessagePort.Worker.(anonymous function).on (internal/worker.js:114:55)
    at MessagePort.emit (events.js:193:13)
    at MessagePort.EventEmitter.emit (domain.js:481:20) code: 'ECANCEL' }
[x] 44
55
66
77
the repl seems to be broken now
...