The problem turned out to be that I was deploying the output from the
webpack build folder rather than the
distribution build folder, and this was missing a key
js
file.
This wasn't
entirely in error, since the earlier (pre-alpha) versions of WASM I was using before didn't output usable
distribution. I can't remember why exactly, but taking the
webpack instead, was a successful workaround at the time.
Anyway,
distribution now works, so switching deployment/copy tasks to that folder fixed everything - leaving here in case it helps another Alpha migrator!