cosmopolitan: redbean: LaunchBrowser not working on macos

redbean 1.5 macos big sur 11.6

If I add in an index.html file then it works fine and I get the server running, but as soon as I add the command LaunchBrowser() to the .init.lua file, it fails with:

error: Uncaught SIGSEGV (SEGV_MAPERR) on Mikas-Mac-Pro pid 5793
  ./redbrean.com.zip
  ENOENT[No such file or directory][2]

I’ve tried with paths "/" and "/index.html" and "index.html" but they all fail with the same issue.