> Maybe the friendly default would be to have the symbolicated reports on

As a comment just below says, the solution is quite simple:

> ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it

Here is the output with the environment variable set.

https://pastebin.com/8M9Dbrgj

This doesn't provide anything useful either.

Seems like there's an architecture error or something, the last line indicates you might have an error with the flag:

> zsh: illegal hardware instruction LLVM_SYMBOLIZER_PATH=/usr/local/opt/llvm/bin/llvm-symbolizer swift main.swift

that's not related to the symbolizer thing. It seems to just be part of the "index out of range" crash. I get the same thing without using the symbolizer.

    zsh: illegal hardware instruction  swift main.swift

Ouch, and yuk. I stand corrected!