Errors

I'll mostly follow the Go style of error being an interface. I may make it a part of the standard library rather than built in - not sure. There will be an easy way to wrap errors. And when debugging a stack is attached to the error when it's created.

Rather than having errors returned as one of several arguments, I'll go with the Rust stye.

Compiler

One useful consequence of the design is that if something is going to cause an immediate catastrophic error, it will be generated statically and can be returned by the compiler rather than ever reaching run time.